Build-Your-Own Tremolo…for Scaredy Cats!

Hi, just saw Shane Speal’s feature article on the 1957 tube driven tremolo plans. Pretty cool! But frankly, high voltage stuff scares the bejeezus out of me… that and my brain can only handle super simple electronics circuits. Other wise it becomes a fog of confusion.

More my speed is a simple little stomp box circuit I found on diystompboxes.com called “The Tiny Trem”:

http://www.diystompboxes.com/smfforum/index.php?topic=87322.0


There’s a YouTube vid of it:

I breadboarded the circuit (quite a while ago) but never built it.

In it’s simplest version as shown in the vero board layout in the first post in the thread I linked to, there are only 6 components (7 with the 2.2k resistor fix) in it’s most simple form and 12 in the most complex version (not including jacks and foot switch) – so it’s cheap to build too.

If you want to mess with this but reading through 42 pages isn’t your cup of tea, here are some notes I made that I gleaned from my own experiments and by reading through the whole thread.

1. MAKE SURE TO KEEP THE CIRCUIT POWER GROUND AND SIGNAL GROUND SEPERATE !

2. The 555 timer chip must be the CMOS type or the circuit will “TICK”.

3. The light/dark values of the LDR used by the author were 5k/1M (respectively). You want a LDR with at least that high of a dark resistance figure. A lower dark value LDR will likely start impacting the tone of your guitar, even with the power removed from the circuit.

4. Use a standard 3mm red or yellow LED for the rate LED – a 5mm may be used so long as it draws 20ma or less (less = better). The effect will lose depth the more drain sucked by this LED.

5. Use a standard/hi bright 5mm red LED with for the LDR – NOT a super bright, they are too low voltage to work properly and super bright LEDs will cause the circuit to “TICK”.

6. Not shown in the original vero board layout and the V1 schematic is a 2.2k resistor between the 555’s pin 3 and the the LED that is the light source for the LDR. This resistor is there to eliminate a “TICKING” problem.

7. A 10k pot between one leg of the LDR LED and ground can be added to provide a DEPTH control.

8. Some of the schematics, perf/vero board and printed circuit diagrams in the thread show the input and output connected differently.

With some, the circuit must be the first one in the stompbox chain – otherwise, the circuit will act like it is bypassed or non-working. The Solution is to have the input connected to one leg of the LDR and the output connected to the other leg of the LDR. This is clearly shown in the very first vero board image in the thread and also in the V1 schematic shown here:

http://www.diystompboxes.com/smfforum/index.php?topic=87322.msg734328#msg734328

If you look at the V2 schematic right below the V1 schematic, you’ll see that the input and output are connected differently – which is OK as long as you always put the tremolo first in the signal chain.

Where this could be critical is if you wish to put the circuit on the input of your cigar box amp as part of the amps circuitry.

9. The most complete, debugged and verified circuit schematic and vero board layout in the thread (and the one I used) can be found here:

http://www.diystompboxes.com/smfforum/index.php?topic=87322.msg840206#msg840206

HOWEVER… note that the input/output as shown might not work as an add-on circuit inside of a cigar box amp or a stompbox latter in the signal chain. If that is your intention, you should hook up the input/output as shown in the V1 vero board layout and schematic.

Well, I hope this was helpful to some of you. Please be aware that I am not currently working on any electronics (I am no expert any way and I’m having too much fun building CBGs right now) so I don’t know if I could help you should you have difficulties, That said this is some pretty simple stuff as far as circuits go and I had no problems.

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