This is the parts list and descriptive text for my layout(s) of the Univibe. I have made two versions, one with the bulb-and-photocell setup of the "original" and one with LED's driving photocells. The bulb-and-photocell is "vibe-a" and the LED version is "vibe-b". As I noted in my original post, there are some changes between the circuitry of this layout the original Univibe circuit. I started with the Univibe circuit from Unicord's service/owner's manual for the Univibe. The signal path is completely unchanged. Let me repeat that. The signal path is completely unchanged. The only changes were in the photoresistors, driver, and power supply. The orignal power supply was half-wave rectified. This led to the need for lots of power filter capacitance to hold hum down. I changed this to full wave rectified and took out a capacitor. I thought that three more diodes was a good trade for one fewer big capacitors. You can leave the diodes out and hack-wire in another capacitor if you like. The original used series R-C filters to make the signal path hum-free. I put in a three-terminal regulator to keep the signal path power clean. This is much cleaner power than the original. Don't try to tell me that additional 60-cycle hum was an important part of the original sound. I stand there snickering if you do. I checked though a lot of catalogs and directories and never found a photocell with a number corresponding to the note on the original schematic. An interested friend who had access to a Univibe was kind enough to measure the resistance swing of the photoresistors at 50K to 250K. I wound up making a version with LED's and phototransistors first, then retrofitting to available incandescent bulbs and photocells per the "original". The 50K-to250K range did not give me a good swing by ear, so I increased the range to 10K to 400K in my prototype. Any method you use to put in a variable resistor that makes that kind of swing will sound the same. The electrons don't know or care whether they're going through cadmium-sulphide, carbon, silicon or whatever. All they know is resistance, capacitance and inductance. If you can't or won't believe that, you're running on superstition. I laid out two different version of the circuit to give you several choices on photoresistors. The vibe-a circuit layout accepts a 12V/40ma grain of wheat bulb and four .250 inch photocells in a layout which fits a cut-down 35mm film canister as a light-tight shield. The vibe-b circuit layout will accept the CLM6000, the Vactec V5C2 or V5C4, and the H11F1 LED to photo-FET optoisolator. You should be able to make any one of these work. The vibe-b will also accept discrete photocells and separate LED's. If you use the vibe-b layout for one of the LED driven methods, you will need to experiment to find out how much LED current gives you how much change in the photocell resistance, then tinker with the driver circuit to get the resistance swing you need. I think that a five-to-one resistance swing is OK. Wider will make the effect more extreme, narrower will be less extreme. The actual resistance that is in the middle of the swing determines the bass-to-treble center position of the effect. The two resistors specified as "39K" in the collector circuit of the driver help determine the static current of the driver transistor and hence the "rest" position of the sweep.. Change these two resistors and trim with the trimpot in the emitter of the driver until you get the resistance center and swing you like. If you use the vibe-a layout, you'll still need to adjust the emitter resistor pot on the driver transistor to get a good light-to-dark swing on the light bulb. From an engineer's point of view, there are some things that look like poor practice in the 'vibe. The half wave rectification is poor economy. Maybe caps were cheaper than diodes back when it was designed. The bulb driver is a poorly stabilized circuit. This thing probably drifts and has wide variations in the originals. On the other hand, the LFO is a neat design, elegant and practical. On the LFO: In the original circuit, the LFO produces a rising amount of signal as the speed goes up. I think this helps to compensate for the decreasing sensitivity of the bulb to changing current as the speed goes up. The back-to-back diodes in the LFO phase shift oscillator circuit seem to be the biggest contributors to this. If you pull these out, the LFO produces a much larger signal and it remains (relatively) constant with speed. There is a 47K resistor specified in series with the base of the driver transistor. If you don't get enough swing on the driver, reduce this to 4.7K, or even to 0. In the vibe-b LED/photocell circuit, pull the diodes out. and increase the 100K resistor from the collector of the driver transistor to its base to between 470K and 750K, again to get the necessary current swing. I provided a space for you to use two transistors as a darlington in the place of the original single transistor if you need more current gain in the driver; there is an intentional short between the base and emitter of this transistor marked with an arrow on the copper pattern. If you use one transistor, leave the short in. If you use two in darlington, cut the short at the arrow. The 250K dual pot should be reverse-log taper to give linear apparent control of speed. 250K dual reverse lot pots are at least as scarce as original "Univibe"'s. I did some math, and put in two 330K resistors that connect from the ends to the wipers of the dual pot. The math says that this will give a good approximation of the reverse log taper if you use a 1M dual linear taper pot, which ought to be a whole lot easier to find. There was an ongoing battle in the audio-engineer world back when phase shifters (for that is what the 'vibe is) were new. The phase shifting capacitors in the shifting stages are staggered in value in the Univibe. An opposing opinion was that shifters with all-the-same cap values would make a more effective phasing sound, and that is the opinion that was finally accepted in the pro-audio world. You can make your own choice by tinkering with the values of the four film phase shifting caps, if you like. Oooops.... but that wouldn't be original, would it???? Resistors All 1/4W unless otherwise noted 150 1 1K 1/2W 1 1K2 1 3K3 2 4K7 17 6K8 1 22K 2 39K 2 (vibe-b only) 47K 8 68K 1 100K 11 220K 2 330K 2 (use with the dual 1M linear taper speed pot) 470k-750k 1 (vibe-b only) 1M2 2 2M2 1 1K pcb mount trimpot (bias adjust for the phasing opto's) - 1 250K dual panel mount pot (LFO speed) -1 (note: you can use a dual 1M linear taper if you use the 330K's) 50K panel mount pot (LFO drive level) -1 100K panel mount pot (output level) - 1 Capacitors 1uF/25V Alum elec. radial pcb mount -16 100uF/25V Alum elec. radial pcb mount -2 220uF/25V Alum elec. radial pcb mount -1 1000uF/25V Alum elec. radial pcb mount -1 330pF film - 1 470pF film - 1 4nF film - 1 15nF film - 1 220nF film - 1 Semiconductors (in order of preference; watch pinout for your choices) input transistor (1) - 2SC539(orignial), 2N5089/2N5210 remainder of signal path (9) - 2SC838c (original) or 2N5210/2N4124/2N3904 /2N2222A/2N4401 I have built one with all 2N3904's except the input transistor, which was a 2N5089. For each darlington pair you can use an integrated darlington pair like the MPS-A13. LFO transistors (2) - 2SC838c (original) or 2N3904/2N4124/2N2222A/2N4401 photocell lamp driver (1) - 2N3904 LFO diodes (2) - 1N914/any silicon diode rectifiers (4) - 1N4001 through 1N4007 7815 three terminal regulator Photoresistors For vibe-b, four of: - CLM6000 LED/photoresistor ($3.50 each, Hosfelt Electronics, see Effects FAQ) - Vactec 5C2 or 5C4 - H11F1/H11F2/H11F3 LED/photo-fet analog isolator (Digi-Key, $1.95 each) - Photocell with 10K to 250K light to dark range (Mouser Electronics, $1.50 each, possibly Radio Shack) and four high brightness green LED's For vibe-a - Four photocells and a 12V/0.04A incandescent bulb (a Radio Shack 8V grain-of-wheat bulb works well) Misc other SPST stomp switch (original) or DPDT stomp switch (true bypass) 2- 1/4" phone jacks for input/output knobs for amplitude and speed jack to match wall wart transformer wall wart transformer, 14-18VAC or 20-25VDC, 50ma or more Light shield if you make vibe-a Box to put it all in To make the light shield for the bulb version: Get a Kodak plastic film canister, black with a grey snap on cap. Remove the cap. On a flat surface place a 1/2" (12mm) spacer and hold the point of a thin, sharp knife blade flat on the spacer so the point sticks a little off the edge of the spacer. Place the closed bottom end of the canister on the flat surface, and slide it over so it touches the point of the blade. Press the canister side into the blade and rotate the canister so the blade cuts into the canister. Do not hold the canister so if you slip or if the canister cuts through suddenly your finger or other personal part will contact the blade. Use light pressure and make several rotations until the canister cuts through. Clean up the edge if needed. Take the now-shortened canister and press the edge of the open end over a relatively sharp corner, as of a table or cabinet, and again rotate the canister, pressing the edge into the edge of the corner. Rotate and press evenly so the corner edge forms the open edge of the canister into a small lip turned outwards. Try to work evenly so the plastic forms into an even lip. The lip is needed so the cap will stay attached; you cut the original plastic lip away when you shortened the canister. Try the cap, and then keep forming the plastic until the cap stays snapped in place. Once the canister is formed, remove the cap. Cut a very small hole exactly in the center of the bottom, smaller than the space between the two holes on the circuit board for the libht bulb. This will be used to align the shield. Take your circuit board and mark a spot exactly in the center of the space between the two holes for the bulb on the component (not copper) side of the board. Cover the bottom of the canister with double sided foam tape, leaving the covering paper on the outside. Cut through the foam tape so you can see through the alignment hole you made in it earlier. Place the canister bottom down on the with the center alignment hole exactly over the alignment mark on the curcuit board between the holes in the circuit board for the bulb. Practice this a couple of times before you remove the covering paper to stick down the canister. When you can do it every time, remove the paper covering the sticky surface of the foam tape on the bottom of the canister and stick it down exactly centered. Turn the board over and use the holes in the circuit board as a guide to drill through the canister bottom so the leads for the bulb and four photocells can pass through the bottom. Now, form the photocell leads so they come about 0.1" out from the back of the photocell and bend at at right angle to be parallel to the body. Stick the leads through from the inside of the canister through to the copper side of the circuit board and solder them in place. When you are done, there will be a little square formed inside the canister by the photocells, with the holes for the bulb in the center. You may have to slightly bend or resolder the leads the get them all nice and neat and the same height, etc. Solder in the bulb in the center of the photocells. When you snap the cap on, the bulb and photocells are held inside the light shield. I recommend doing all this is two phases: Make the shortened canister and place it on the board and drill the holes before you place any other components on the board. Solder the photocells and bulb in after all other components are on the board.