I tried to make this homemade VHF receiver in a “retro” style. Front End from car radio. KSE marking. Next, the IF unit on the KIA 6040, the ULF on the tda2006, the 3GD-40 speaker, in front of which there is a 4-5 kHz notch, I don’t know exactly, I selected it by ear.
Radio receiver circuit
I don’t know how to do digital tuning, so it will just be a variable resistor; for this VHF unit, 4.6 volts is enough to completely cover 87-108 MHz. Initially I wanted to insert an ULF on P213 transistors, since I had assembled and rebuilt the “retro” one, but it turned out to be too bulky, so I decided not to show off.
Well, a surge filter is installed, of course it won’t hurt.
There was no suitable dial indicator, or rather there was one, but it was a pity to install it - there were only 2 left, so I decided to remake one of the unnecessary M476s (as in Ocean-209) - I straightened the needle and made a scale.
Backlight - LED Strip Light. The vernier is assembled from parts of various radios, from tube radios to China. The entire scale with the mechanism is removed, its body is glued together from many wooden parts, rigidity is given by the textolite on which the scale is glued and all this is pulled to the body of the receiver, simultaneously additionally pressing the front panels (those with a mesh), which are also removable if desired.
Scale under glass. The tuning knobs are from some radio from a junkyard, tinted.
Overall, a flight of fancy. I have long wanted to try out the curvature of my hands by building something similar. And here there was absolutely nothing to do, and scraps of plywood from the renovation remained, and the mesh turned up.
Since ready-made vintage cases in good condition are already difficult to get, I made a homemade replica; in our outback, all the vintage rotted away in the garages long ago. Inspired by this photo:
Discuss the article HOMEMADE RADIO IN RETRO STYLE
Project "Vintage"
The idea of creating a media center for a summer residence was born quite a long time ago. I decided to take an old Soviet radio as a basis. Well, I am drawn to everything Soviet, you can see this by looking at the post with my previous development.
I received the radio from the Riga VEF plant in excellent condition. And if you consider that this same radio was produced in 1965, then the project simply had to be implemented.
What is noteworthy is that the radio was in full working order. And we even experimented a little with connecting an electric guitar to it.
Let's start smoking. Breaking is not building)))
Friends came to the rescue.
Don’t feed them bread at all, just give them something to sort out.
And now our device is nothing more than a wooden box.
At first there was an idea to place car speakers and a homemade/purchased amplifier inside, but then it was decided that it would be easier and cheaper to buy a 2.1 system, for which we went to a computer store.
To implement the project it was chosen acoustic system Logitech, for perfect ratio price quality.
The insides will be from a very old, but working computer.
In general, the concept is built on preserving completely original look with modern filling. In my case appearance will differ from the original only in the bass reflex built into the side wall and the 15" LCD monitor in the regular place of the vinyl player.
I cut out part of the glued timber and make a hole for the future bass reflex.
To ensure proper sealing between the body of the radio and the subwoofer, I glue a rubber o-ring. I cut it out of a record player cover. Despite its age, the rubber is very soft and elastic.
Embedding the speakers into the facade was one of the most labor-intensive processes. Due to the completely glued body, it was not possible to remove the decorative fabric. I had to make a cut in the part covered by the original plug and very carefully mill out the seats without damaging the textiles.
From an outer corner purchased at a hardware market, I cut out a decorative overlay for the monitor.
After all parts of the decorative frame were adjusted, it was glued with PVA and opened with varnish.
Meanwhile, I set about implementing management. The old but working keyboard was completely disassembled. Using an improvised tester (power supply + light bulb), the contacts responsible for certain buttons were calculated. Because the system will work on the "Mediaportal" program; control requires only seven buttons.
A friend came to help with soldering the so-called “i-Bar”.
We were unable to identify all the buttons correctly at once. Of the seven buttons, only three performed the necessary actions. We double-checked the contacts and re-soldered the buttons.
Three more times I had to cut and re-glue the microbuttons themselves.
Later I transferred the diagram and buttons to another, more aesthetic block.
Installation work with a telephone connected to the speaker for sound control.
Well, how could we do without it...
DIY steampunk radio. Let's continue the topic of the second life of outdated gadgets. At one time, FM radios with simple electronic settings consisting of two buttons “Scan” and “Reset” were popular. Such a receiver can become the basis for an interesting design of a loud-speaking receiver, very suitable for use in the workplace, thanks to its compact size and local voice-over of the workplace. The most difficult part of being a radio amateur is not always making electronic filling, but the production of a strong and successful case for housing the soldered item. To give the receiver a second life, an attempt was made to make a case in the steampunk style. See what came out of this below.
How to make a steampunk hull
Please do not judge strictly - this is the first attempt. In addition to developing a stylish housing for the radio, the goal was to minimize costs and use available components and materials. Moreover, the materials are easy to process.
Before starting work, let's study the receiver's controls, which will need to be placed on the body. As mentioned above, these are two tuning buttons “Scan” - tunes the station after each press from the last radio station to the next radio station higher in the range. When tuning to the latest radio station, returning to the beginning of the range is done by pressing the “Reset” button. In the original receiver, the third button turns on the flashlight (it was not an LED, but a light bulb!) and is not used in this design. The volume of receiving stations is regulated by a potentiometer combined with the power switch. sound signal goes to the headphones, of course there is no speech in any stereo signal in such a receiver. The headphone cord is also an antenna for the radio. Controls can be purchased at a store or used from old equipment. Controls were purchased for this design; the total price of two buttons, a switch, an antenna terminal and a potentiometer (30 kOhm) with a knob did not exceed 150 rubles (2013). A sensitive loudspeaker extracted from a small-sized speaker was used as a loudspeaker. Head resistance 8 ohms.
Column - donor 
Speaker 1. The body is based on a piece of white polystyrene sheet measuring 200x130 mm and 1.5 mm thick. The sheet contains markings for controls and body bends to form side walls with a height of 40 mm. Possible options for using plastic housings distribution boxes purchased at an electrical goods store.
2. On the inside, following the marking of the bend of the walls, small cuts are made, for example, with the sharp end of scissors or a knife, 1/4 - 1/3 of the thickness of the plastic.
3. Gas lighter evenly We heat the entire bend until the plastic softens and form the side wall. The flame should not reach the bend point 10-15 mm. This will result in the most intense heating. We perform the same operation with the second wall. The resulting “U”-shaped body should rest with all ends of the side walls on the surface.
Body parts 
Marking the workpiece 
4. After making the body, you can make holes. The sound from the speaker will be transmitted towards the listener through the bell. A siphon was used as a socket to remove water from the floor (made in Spain :)). Hole for speaker - bell can be drilled thin drill and then trim with a knife.
5. The front and back walls are cut out with your own hands using tailor’s scissors, also from sheet polystyrene and glued with glue for gluing plastic models.
6. We process the gluing seams with fine sandpaper to smooth out the edges.
7. The drain is made of an unknown plastic and it was not possible to glue it. To maintain the style, the included threaded clamp was used, which was attached to the body with hot-melt adhesive from the inside. At the same time, we secure the loudspeaker with hot glue.
Holes in the housing 
The clamp is secured 
Receiver body 8. We install control elements into the resulting housing. We use from the old receiver battery compartment, from which we remove unnecessary plastic.
9. Using a soldering iron, carefully remove the potentiometer from the receiver board and solder the extension conductors for:
— setting buttons;
- loudspeaker;
— volume control potentiometer;
— power switch;
— power supply for the receiver, minus to the switch, plus to the battery compartment;
— antennas, it is better to wrap the antenna wire around a pencil and place it, slightly stretched, in the receiver body, so you may not need to connect an external antenna.
10. Solder the conductors to the controls. We insert the batteries. We check the operation of the receiver; if there is no mistake anywhere, the electronics will work immediately.
11. Secure the board, battery compartment and antenna inside the case with hot glue. Look at the photo. Cut out the bottom cover from corrugated cardboard. The retro radio is ready.
The board is connected 
Receiver basement 
Within the city limits, the radio receiver receives almost all stations; in the suburbs, the number of received stations may decrease and you will need to connect an external antenna; a piece of wire up to a meter long should be enough. Do not expect high volume from the receiver; if you need to increase the volume, you need to build in an amplifier. An example of an amplifier is given
Recently, there has been a lot of interest in antique and retro radio equipment. The collections include both retro radio equipment from the 40-60s and real antique radio equipment from the 10-30s. In addition to collecting original products, there is a growing interest in collecting and making so-called replicas. This is a very interesting area of amateur radio creativity, but first let’s explain the meaning of this term.
There are three concepts: original, copy and replica of an antique product. The term "original" does not need any description. A copy is a modern repetition of an antique product, down to the smallest details, materials used, design solutions, etc. A replica is a modern product made in the style of products of those years and, if possible, with approximations constructive solutions. Accordingly, the closer the replica is to the original products in style and detail, the more valuable it is.
Nowadays there are many so-called radio souvenirs on sale, mostly made in China, designed in the form of retro and even antique radio equipment. Unfortunately, upon closer examination it is clear that its value is low. Plastic handles, painted plastic, the body material is covered with MDF film. All this speaks of a very low-grade product. As for their “filling”, it usually consists of printed circuit board with modern integral elements. Internal installation Such products also leave much to be desired in terms of quality. The only “advantage” of these products is their low price. Therefore, they may be of interest only to those who, without going into technical details or simply not understanding them, he wants to have an inexpensive “cool thing” on his desk in his office.
As an alternative, I would like to present a receiver design that fully meets the requirements of an interesting and high-quality replica. This is a super-regenerative tube VHF FM receiver (Fig. 1), operating in the frequency range 87...108 MHz. It is assembled on octal series radio tubes, since it is not possible to use pin-base tubes in this design, which are older and suitable in style, due to the high operating frequency of the receiver.
Rice. 1. Super regenerative tube VHF FM receiver
Bronze terminals, control knobs and brass nameplates are an exact copy of those used in products of the 20s of the last century. Some elements of fittings and design are original. All radio tubes of the receiver are open, except for the screens. All inscriptions are made on German. The receiver body is made of solid beech. The installation, with the exception of some high-frequency components, is also made in a style as close as possible to the original of those years.
The front panel of the receiver contains a power switch (ein/aus), a frequency setting knob (Freq. Einst.), and a frequency scale with a tuning pointer. The top panel has a volume control (Lautst.) on the right and a sensitivity control (Empf.) on the left. Also on the top panel there is a dial voltmeter, the backlight of which indicates that the receiver is powered on. On the left side of the housing there are terminals for connecting an antenna (Antenne), and on the right there are terminals for connecting an external classical or horn loudspeaker (Lautsprecher).
I would like to note right away that the further description of the receiver device, despite the presence of drawings of all the parts, is for informational purposes only, since the repetition of such a design is accessible to experienced radio amateurs, and also presupposes the presence of certain wood and metalworking equipment. In addition, not all elements are standard and purchased. As a result, some installation dimensions may differ from those shown in the drawings, since they depend on those elements that are available. For those who want to repeat this receiver “one-on-one” and who will need more detailed information about the design of certain parts, assembly and installation, drawings are offered, as well as the opportunity to ask a question directly to the author.
The receiver circuit is shown in Fig. 2. The antenna input is designed to connect a symmetrical reduction cable to a VHF antenna. The output is designed to connect a loudspeaker with a resistance of 4-8 Ohms. The receiver is assembled according to the 1-V-2 circuit and contains a UHF on the VL1 pentode, a super-regenerative detector and a preliminary ultrasonic on the VL3 double triode, a final ultrasonic on the VL6 pentode and a power supply on the T1 transformer with a rectifier on the VL2 kenotron. The receiver is powered from a 230 V network.
Rice. 2. Receiver circuit
UHF is a range amplifier with spaced circuit tuning. Its tasks are to amplify high-frequency oscillations coming from the antenna and to prevent the penetration of the super-regenerative detector’s own high-frequency oscillations into it and radiation into the air. The UHF is assembled on a high-frequency pentode 6AC7 (analogue - 6Zh4). The antenna is connected to the input circuit L2C1 using the L1 coupling coil. The input impedance of the cascade is 300 Ohms. The input circuit in the grid circuit of the VL1 lamp is set to a frequency of 90 MHz. The setting is carried out by selecting capacitor C1. Circuit L3C4 in the anode circuit of lamp VL1 is tuned to a frequency of 105 MHz. The setting is carried out by selecting capacitor C4. With this configuration of the circuits, the maximum UHF gain is about 15 dB, and the unevenness of the frequency response in the frequency range 87...108 MHz is about 6 dB. Communication with the subsequent cascade (super-regenerative detector) is carried out using coupling coil L4. Using variable resistor R3, you can change the voltage on the screen grid of the VL1 lamp from 150 to 20 V and thereby change the UHF transmission coefficient from 15 to -20 dB. Resistor R1 serves to automatically generate a bias voltage (2 V). Capacitor C2, shunt resistor R1, eliminates feedback by alternating current. Capacitors C3, C5 and C6 are blocking. The voltages at the terminals of the lamp VL1 are indicated for the upper position of the resistor R3 engine in the diagram.
Super regenerative detector assembled on the left half of a double triode VL3 6SN7 (analogue - 6N8S). The superregenerator circuit is formed by inductor L7 and capacitors C10 and C11. Variable capacitor C10 is used to adjust the circuit in the range of 87...108 MHz, and capacitor C11 is used to “set” the boundaries of this range. The grid circuit of the super-regenerative detector triode includes a so-called “gridlick” formed by capacitor C12 and resistor R6. By selecting capacitor C12, the damping frequency is set to about 40 kHz. The super-regenerator circuit is connected to the UHF using communication coil L5. The supply voltage of the anode circuit of the superregenerator is supplied to the outlet of the loop coil L7. Choke L8 is the load of the superregenerator at high frequency, choke L6 is at low frequency. Resistor R7 together with capacitors C7 and C13 form a filter in the power circuit, capacitors C8, C14, C15 are blocking ones. The AF signal through capacitor C17 and low-pass filter R11C20 with a cutoff frequency of 10 kHz is supplied to the input of the preliminary ultrasonic filter.
Preliminary ultrasound assembled on the right (according to the diagram) half of the triode VL3. The cathode circuit includes resistor R9 for automatically generating a bias voltage (2.2 V) on the grid and inductor L10, which reduces the gain at frequencies above 10 kHz and serves to prevent the penetration of superregenerator damping pulses into the final ultrasonic frequency. From the anode of the right triode VL3, through the isolation capacitor C16, the AF signal is supplied to the variable resistor R13, which serves as a volume control.
The power supply provides power to all components of the receiver: alternating voltage 6.3 V - to power the filament lamps, constant unstabilized voltage 250 V - to power the anode circuits of the UHF and the final ultrasonic frequency. The rectifier is assembled using a full-wave circuit on a VL2 5V4G kenotron (analogue - 5Ts4S). Rectified voltage ripples are smoothed out by the C9L9C18 filter. The supply voltage of the super-regenerator and preliminary ultrasonic amplifier is stabilized by a parametric stabilizer based on resistor R14 and gas-discharge zener diodes VL4 and VL5 VR105 (analogue - SG-3S). The R12C19 RC filter additionally suppresses voltage ripple and zener diode noise.
Design and installation. The UHF elements are mounted on the main receiver chassis around the lamp panel. To prevent self-excitation of the cascade, the grid and anode circuits are separated by a brass screen. The communication coils and loop coils are frameless and mounted on textolite mounting racks (Fig. 3 and Fig. 4). Coils L1 and L4 are wound with silver-plated wire with a diameter of 2 mm on a mandrel with a diameter of 12 mm with a pitch of 3 mm.
Rice. 3. Communication coils and loop coils are frameless, mounted on textolite mounting racks
Rice. 4. Communication coils and loop coils are frameless, mounted on textolite mounting racks
L1 contains 6 turns with a tap in the middle, and L4 contains 3 turns. Contour coils L2 (6 turns) and L3 (7 turns) are wound with silver-plated wire with a diameter of 1.2 mm on a mandrel with a diameter of 5.5 mm, the winding pitch is 1.5 mm. The loop coils are located inside the communication coils.
The screen grid voltage of the VL1 lamp is controlled by a dial voltmeter located on the top panel of the receiver. The voltmeter is implemented on a milliammeter with current total deviation 2.5 mA and additional resistor R5. Subminiature scale backlight lamps EL1 and EL2 (СМН6.3-20-2) are located inside the milliammeter housing.
Rice. 5. Elements of a super-regenerative detector and preliminary ultrasonic sounder, mounted in a separate shielded block
The elements of the super-regenerative detector and preliminary ultrasonic sounder are mounted in a separate shielded block (Fig. 5) using standard mounting racks (SM-10-3). Variable capacitor C10 (1KPVM-2) is fixed to the block wall using glue and a textolite sleeve. Capacitors C7, C8, C14 and C15 are feedthrough series KTP. Inductor L6 is connected through capacitors C7 and C8. The supply voltage to the shielded unit is supplied through capacitor C15, and the filament voltage is supplied through capacitor C14. Oxide capacitor C19 - K50-7, inductor L8 - DPM2.4. The L6 choke is homemade, it is wound in two sections on a magnetic circuit Ш14х20 and contains 2х8000 turns of PETV-2 0.06 wire. Since the choke is sensitive to electromagnetic interference (in particular, from power supply elements), it is mounted on a steel plate above the UHF (Fig. 6) and covered with a steel screen. It is connected with shielded wires. The braid is connected to the body of the super-regenerator unit. To manufacture the L10 inductor, an SB-12a armored magnetic circuit with a permeability of 1000 was used; a winding of 180 turns of PELSHO 0.06 wire was wound on its frame. Coils L5 and L7 are wound with silver-plated wire with a diameter of 0.5 mm in increments of 1.5 mm, on a ribbed ceramic frame with a diameter of 10 mm, which is glued using a textolite sleeve into the hole of the lamp panel. Inductor L7 contains 6 turns with a tap of 3.5 turns, counting from the top one in the output diagram, communication coil L5 - 1.5 turns.
Rice. 6. Choke mounted on steel plate above UHF
The shielded unit is secured to the main receiver chassis using a threaded flange. The connection between capacitor C16 and resistor R13 is made with a shielded wire with the shielding braid grounded near resistor R13. The rotation of the rotor of the C10 capacitor is carried out using a textolite axis. To ensure the necessary strength and wear resistance of the splined connection of the axle and the C10 capacitor, a cut was made in the axle into which a fiberglass laminate plate was glued. One end of the plate is sharpened so that it fits tightly into the slot of the C10 capacitor. The axle is fixed and pressed against the capacitor slot using a spring washer placed between the bracket bushing and the driven pulley fixed to the axle (Fig. 7).
Rice. 7. Shielded block
The vernier is assembled on two brackets fixed to the front wall of the shielded superregenerator block (Fig. 8). The brackets can either be made independently, according to the attached drawings, or use a standard aluminum profile with minor modifications. To transmit rotation, a nylon thread with a diameter of 1.5 mm is used. You can use a “severe” shoe thread of the same diameter. One end of the thread is attached directly to one of the pins of the driven pulley, and the other to the other pin through a tension spring. Three turns of thread are made in the groove of the vernier's driving axis. The driven pulley is fixed on the axis so that in the middle position variable capacitor C10, the end hole for the thread was located diametrically opposite to the leading axis of the vernier. Both axles are fitted with extension attachments secured to them with locking screws. A frequency adjustment knob is installed on the drive axis attachment, and a scale dial indicator is installed on the driven axis attachment.
Rice. 8. Vernier
Most elements of the final ultrasonic amplifier are mounted on the terminals of the lamp panel and mounting racks. The output transformer T2 (TVZ-19) is installed on an additional chassis and oriented at an angle of 90° relative to the magnetic circuit of the inductor L9 of the power supply. The connection between the control grid of the VL6 lamp and the motor of resistor R13 is made with a shielded wire with grounding of the shielding braid near this resistor. Oxide capacitor C21 - K50-7.
The power supply (except for elements L9, R12 and R14, which are mounted on an additional chassis) is mounted on the main chassis of the receiver. Unified choke L9 - D31-5-0.14, capacitor C9 - MBGO-2 with flanges for mounting, oxide capacitors C18, C19 - K50-7. For the manufacture of transformer T1 with an overall power of 60 VA, a magnetic circuit Ш20х40 was used. The transformer is equipped with stamped metal covers. The VL2 kenotron panel is installed on the top cover along with a brass decorative nozzle (Fig. 9). A mounting block is installed on the bottom cover, where the necessary terminals of the transformer windings and the terminal of the kenotron cathode are brought out. The power transformer is attached to the main chassis with studs that tighten its magnetic circuit. The stud nuts are four threaded posts on which the additional chassis is attached (Fig. 10).
Rice. 9. VL2 kenotron panel together with a brass decorative nozzle
Rice. 10. Additional chassis
The entire installation of the receiver (Fig. 11) is carried out with a single-core copper wire with a diameter of 1.5 mm, placed in a varnished fabric tube different colors. Its ends are fixed using nylon thread or pieces of heat-shrinkable tubing. The assembly wires assembled into bundles are connected to each other with copper clamps.
Rice. 11. Mounted receiver
Before installation, transformer T1 and capacitors C13, C18, C19 and C21 are painted with a spray gun with “Hammerite hammer black” paint. The power transformer is painted in a tightened state. When painting capacitors, it is necessary to protect the lower part of their metal casing, which is adjacent to the chassis. To do this, before painting, the capacitors can, for example, be mounted on a thin sheet of plywood, cardboard or other suitable material. Before painting the power transformer, it is necessary to remove the decorative brass cap and protect it masking tape from the paint the kenotron panel.
The receiver body is wooden and made of solid beech. Side walls connected by finger joint in increments of 5 mm. The front part of the case is lowered to accommodate the front panel. In the lateral and back walls The housing has rectangular holes. The outer edges of the holes are machined with an edge radius cutter. On the inner edges of the holes there are undercuts for fastening the panels. In the side openings of the case there are panels with contact input and output terminals, and in the rear there is a decorative grille. The upper and lower parts of the body are also made of solid beech and finished with edge cutters. All wooden parts are tinted with mocha stain, primed and varnished by professional paint and varnish materials(paintwork) from Votteler with intermediate grinding and polishing according to the instructions supplied with the paintwork.
The front panel is painted with “Hammerite black smooth” paint using a technology that produces a large, clearly defined shagreen (large-droplet spraying onto a heated surface). The front panel is secured to the receiver body with brass self-tapping screws of appropriate sizes with a semicircular head and a straight slot. Similar brass fasteners are available in some hardware stores. All nameplates are custom-made and made on a CNC machine with laser engraving on brass plates 0.5 mm thick. They are attached to the front panel using M2 screws, and to wooden panel- brass self-tapping screws.
After assembling the receiver and checking the installation for possible errors you can start making adjustments. To do this, you will need a high-frequency oscilloscope with an upper limit frequency of at least 100 MHz, a capacitor capacitance meter (from 1 pF) and, ideally, a spectrum analyzer with a maximum frequency of at least 110 MHz and a sweep frequency generator (SWG) output. If the analyzer has an output spectrum of the MFC, it is possible to observe the frequency response of the objects under study. A similar device is, for example, the SK4-59 analyzer. If this is not available, you will need an RF generator with the appropriate frequency range.
A correctly assembled receiver begins to work immediately, but requires adjustment. First check the power supply. To do this, remove lamps VL1, VL3 and VL6 from the panels. Then a load resistor with a resistance of 6.8 kOhm and a power of at least 10 W is connected in parallel with capacitor C18. After turning on the power supply and warming up the kenotron VL2, the gas-discharge zener diodes VL4 and VL5 should light up. Next, measure the voltage on capacitor C18. With an unloaded filament winding, it should be slightly higher than indicated in the diagram - about 260 V. At the anode of the zener diode VL4, the voltage should be about 210 V. The alternating filament voltage of radio tubes VL1, VL3 and VL6 (if they are absent) is about 7 V. If all the given above the voltage value is normal, the test of the power supply can be considered complete.
Unsolder the load resistor and install lamps VL1, VL3 and VL6 in their places. The sensitivity control slider (resistor R3) is set to the top position according to the diagram, and the volume control (resistor R13) is set to the minimum volume position. A dynamic head with a resistance of 4...8 Ohms is connected to the output (terminals XT3, XT4). After turning on the receiver and warming up All radio tubes are checked for voltage on their electrodes in accordance with those indicated in the diagram. When the volume is increased by turning resistor R13 in the loudspeaker, the characteristic high-frequency noise of the operation of the super-regenerator should be heard. Touching the antenna terminals should be accompanied by increased noise, which indicates the proper operation of all stages of the receiver.
The setup begins with a super-regenerative detector. To do this, remove the screen from the VL3 lamp and wind a communication coil around its cylinder - two turns of a thin insulated mounting wire. Then install the screen back by releasing the ends of the wire through the top hole of the screen and connecting the oscilloscope probe to them. If the super-regenerator is operating correctly, characteristic flashes of high-frequency oscillations will be visible on the oscilloscope screen (Fig. 12). By selecting capacitor C12 it is necessary to achieve a flash repetition rate of about 40 kHz. When adjusting the receiver over the entire range, the flash repetition rate should not change noticeably. Then they check the tuning range of the super-regenerator, which determines the tuning range of the receiver, and correct it if necessary. To do this, instead of an oscilloscope, a spectrum analyzer is connected to the ends of the communication winding. The selection of capacitor C11 sets the boundaries of the range - 87 and 108 MHz. If they differ greatly from those indicated above, it is necessary to slightly change the inductance of coil L7. At this point, setting up the super regenerator can be considered complete.
Rice. 12. Oscilloscope readings
After adjusting the super-regenerator, remove the communication coil from the VL3 lamp cylinder and proceed to establishing the UHF. To do this, you need to unsolder the wires going to the inductor L6, remove the inductor itself and the plate on which it is attached (see Fig. 6) from the chassis. This will open access to the UHF installation and turn off the super-regenerator cascade. Disabling the super-regenerator is necessary so that its own oscillations do not interfere with the UHF tuning. The output of the spectrum analyzer (or the output of the RF generator) is connected to one of the extreme and middle terminals of the inductor L1. The input of a spectrum analyzer or an oscilloscope is connected to the L4 coupling coil. It should be recalled that connecting devices to the receiver elements must be done with coaxial cables of minimum length, cut on one side for soldering. The termination ends of these cables should be as short as possible and soldered directly to the terminals of the corresponding elements. It is strictly not recommended to use oscilloscope probes to connect devices, as is often done.
By selecting capacitor C1, tune the UHF input circuit to a frequency of 90 MHz, and the output circuit by selecting capacitor C4 to a frequency of 105 MHz. It is convenient to do this by temporarily replacing the corresponding capacitors with small-sized trimmers. If a spectrum analyzer is used, the adjustment is performed by observing the real frequency response on the analyzer screen (Fig. 13). If an RF generator and an oscilloscope are used, first adjust the input circuit, and then the output circuit according to the maximum signal amplitude on the oscilloscope screen. After completing the setup, you must carefully unsolder the tuning capacitors, measure their capacitance and select permanent capacitors with the same capacitance. Then you need to recheck the frequency response of the UHF cascade. At this point, setting up the receiver can be considered complete. It is necessary to return the inductor L6 to its place and connect it, check the operation of the receiver over the entire frequency range.
Rice. 13. Analyzer readings
The operation of the receiver is checked by connecting an antenna to the input (terminals XT1, XT2), and a loudspeaker to the output. Keep in mind that a super regenerative detector can only receive FM signals on the slopes of its circuit's resonance curve, so there will be two settings for each station.
If an authentic horn manufactured in the 20s of the last century is intended to be used as a loudspeaker, it is connected to the output of the receiver through a step-up transformer with a voltage transformation ratio of about 10. You can do otherwise by connecting the horn capsule directly to the anode circuit of the VL6 lamp. This is how they were connected to receivers in the 20s and 30s. To do this, the output transformer T2 is removed and terminals XT3 and XT4 are replaced with a 6 mm "Jack" socket. The wiring of the socket and plug of the horn cord must be done so that the anode current of the lamp, passing through the coils of the horn capsule, enhances the magnetic field of its permanent magnet.
and why the hell bother with something like that? take a ready-made VHF-IP2 block from the old one tube receiver. UPCHZ from any TV and a regular FM converter to K174ps1 use any UCH on lamps. assemble into the same building. fast, cheap and cheerful
Once upon a time we assembled our first simple radios in school age from sets. Today, due to the development of modular design, it is not difficult to assemble a digital radio receiver even for people who are extremely far from amateur radio. This receiver's design is based on the impressive 1935 AWA radio that the author came across in the book Deco Radio: The Most Beautiful Radios Ever Made. The author was so impressed by its design that he wanted to have his own analogue.
The design uses a Nokia 5110 LCD display to display the frequency and an encoder to select it. The volume is controlled by a variable resistor built into the amplifier. To emphasize the design, the author also used an Art Deco style font to display information on the display. The Arduino code contains a function for remembering the last station listened to (which was listened to for more than five minutes).
Step 1: Components
- Arduino Pro Mini
- FTDI programmer
- TEA5767 FM radio module
- Speaker 3W
- PAM8403 amplifier module
- Encoder
- Nokia 5110 LCD display
- Battery charge and protection board
- 18650 battery
- Holder 18650
- Switch
- Breadboard 5x7 cm
- Connecting wires
- Speaker fabric
First of all, if you don't have great experience When working with Arduino, you should first assemble the circuit using a non-printed breadboard. In this case, for convenience, you can use Arduino Nano or UNO. Personally, at the stage of debugging circuits, I use Arduino UNO, since it, together with development board convenient to use for connecting the necessary components, practically without using soldering. When you turn on the device, the logo should be displayed on the screen for a few seconds, after which the frequency of the last listened station is loaded from the EEPROM memory. By turning the encoder knob you can adjust the frequency by changing stations.
When everything works well on the breadboard, you can move on to the main assembly, using the more compact and cheaper Arduino PRO Mini, which, moreover, has lower consumption. But before that, let's see how everything will be located in the case.
Step 3: Design the Case
The 3D model was developed in the free but quite powerful Fusion 360 program.
Step 4: 3D Printing and Processing
FormFutura "wooden" plastic was used for printing. This is a rather unusual plastic, the peculiarity of which is that after printing the parts have a look similar to wood. However, when printing with this plastic, the author encountered a number of problems. Small parts printed without problems, but the body, the largest part, did not print the first time. When trying to print it, the nozzle constantly became clogged, the situation was aggravated by regular power failures, which is why the author even had to purchase a UPS for the printer. Ultimately, the body was printed on top of the unprinted blank. This solution, however, is not really a solution to the problem, just a one-time way out of the situation, so the question remains open. Since the print did not work out successfully, the author then decided to sand the body, putty it with wood putty and varnish it. Yes, this plastic doesn’t just look like wood, it’s essentially fine wood dust mixed with a binder plasticizer, so the parts printed with it are practically wooden and can be processed using ordinary wood.
Step 5: Putting it all together
The next step is to install the electronics into the housing. Since everything has already been modeled in Fusion 360, this won't be a problem. As you can see, each component has its own position in the case. The first step was to unsolder the Arduino Pro Mini, after which the code was loaded into it. The next step is the power source. The project used a very convenient and compact Wemos board, which is simultaneously responsible for charging the battery, protecting it, and also increases the voltage for consumers to the required 5 volts. Instead, you can use a conventional charge and protection module, and increase the voltage with a separate DC/DC converter (for example TP4056 + MT3608).
Next, the remaining components, speaker, display, and amplifier are soldered. Also, even though there are power supply capacitors on the amplifier module, it is advisable to add another one (the author set it to 330 uF, but 1000 is also possible). The sound quality (if 10% THD can be called quality) of the sound of the PAM8403 amplifier very much depends on the power supply, as does the operation of the radio module. When everything is soldered and tested, you can start final assembly. First of all, the author glued the grille and radio fabric on top of it.
Push. Radio fabric is a specific thing, and every stall does not sell it. However, in every women's needlework store you can buy such a thing as canvas (fabric for cross stitch). It is inexpensive and very suitable as a replacement for radio fabric, sometimes different colors. Take natural (not synthetic) and with the largest cell. By the way, it fits perfectly with the design of this radio.
All other boards are secured in place using hot-melt adhesive. You can use hot glue a lot, but it works really well for these purposes, considering that most modules do not have mounting holes. Although I prefer to use double-sided "car" tape for these purposes.
Step 6: Firmware
This step should have been placed higher, since it needs to be flashed at the debugging stage. The basic idea of the code is this: when the encoder knob is turned, the frequency is searched, when the encoder knob remains in the same position for more than 1 second - this frequency is set for the FM receiver module.
If(currentMillis - previousMillis > interval) ( if(frequency!=previous_frequency) ( previous_frequency = frequency; radio.selectFrequency(frequency); seconds = 0; )else
The FM radio module takes about 1 second to tune to a new frequency, so it will not be possible to change the frequency in real time by turning the encoder knob, because in this case, the tuning of the receiver will be very slow.
