ROG modified EA Tremolo parts substitution

[Fndr8875]

ok, ive searched google, this forum, everything and im a little confused.

Here is the circuit im building:

http://tagboardeffects.blogspot.com/search?q=EA+tremolo


It calls for 3 1uf film caps, which from looking at vero layout seem to do with Depth, which calls for 250k linear pot. I have some .47 film capacitors, 2 types, some massive greenies, and some small Kemet ones. Im not gonna put two of them parellel for space reasons and bc id be one short and dont wanna use all this value up out of my parts stash. I found a post from someone with same issue, no 1uf films, and someone relpied to just use .1 or 100nf film caps, and poster said it worked. This was with GGG EA tremelo i think , which is a slightly different circuit. So do i use 2 1uf electrolytics in series wired  + - - +, substitute 100nf in place of the 1uf, or substitute .47 films. I only have a 500k linear pot, so i think using .47 films and the 500k pot, instead of 250k pot and 1ufs , will that work out same? I get confused sometimes and do things a little backwards cuse feel like my brain is overloaded. I just build a Cavedweller Delay on vero from same site, it called for 1uf film and I used 2 .47 electros in series , like i said i was worn out from several hours of building pedal, this was on vero that had 3 cuts in wrong place, that happened to call for components to go in places where wrong cuts were. I was shocked that it works perfectly after bridging those wrong cuts, and then realizing the .47 series electros. I know u gotta do parallel with caps, i had to use two 22nfs because i didnt have a 47 nf, any way back to original subject, will .47 films and 500k pot work fine , please give me some ideas, ive got all resistors in everything ready to go, ill experiment if no one replies, but would really like to just do this once, have a habit of messing up circuits because i used to be MOD happy, anyway thanks for any replies

[Jdansti]

You can get 1uf film caps from Tayda.

http://www.taydaelectronics.com/capacitors/polyester-film-box-type-capacitors/1uf-100v-5-polyester-film-box-type-capacitor.html

[Fndr8875]

i know i can order them, im going on vacation in 2 days and just wanted to finish and play with this before i left. Im to impatient to wait on tayda shipping, i normally just order from thaishine on ebay and i can get it in 4 days. Well i think im gonna just stick some sockets on it and try out the .47 films i have and the .1 that i read someone substituted and it worked fine. Ive built some pedals before on vero, but not to point where i understand what each part is doing. I think from the layout that the 1uf films are going out to depth pot, can anyone help out  if my thinking is right?

[Jdansti]

No capacitors are connected to the depth pot. By looking at the points where the pot terminals connect and following the traces (tracks) I see the following:

Depth 1 is only connected to a 68k resistor which is connected on the other end to two transistors.
Depth 2 is only connected to one of the transistors.
Depth 3 is only connected to a 120k resistor.

If you follow the traces where each pot wire is connected, you can see what they are connected to. When you follow a trace that has a cut, then the connection stops at that point and doesn't continue across the cut. If you follow a trace and come to a jumper, then follow that jumper to another trace. Of course, the connection might continue along the trace beyond the jumper until you come to a cut or the end of the trace. It's very much like following traces on a PCB, except all of the traces are in straight parallel rows.

[antonis]

The 3 X 1μF caps set the time constant(s) for the Low Frequency Oscillator. Using 470nF instead you roughly half it.
(not exactly but for the shake of simplicity..)

Your tremolo should work fine but you'll able to get "half" Rate settings (blinking frequency).

If you want to approach original settings with your capacitors, try with a 250k Rate pot & 33k resistor...
(leave 2M2 as it is because a 4M7 may shouldn't be able to provide enough current on Q3's base - after all it's role on time constant is almost negligible compared with the other resistor values..)

[duck_arse]

I can't see a circuit diagram, so I'll probably make a goose of myself, but - I don't think you'll get a steady oscilllation from the circuit if you use larger than 100k (+ the small stopper resistor) as the rate pot. if you only have 500k, wire a 120k or 150k across the cw and ccw (short wiper to ccw) lugs to bring it down some. it may still oscillate, then fade away at the far slow end, this means too much pot resistance or too little of the fixed resistance in 'the other leg'.

the three caps are the phase-shifters, as antonis says, the circuit works best when they are all the same value, whatever it happens to be. and changing the fixed R (I think 15k? no circuit ....) up to maybe 33k or 47k will slow somewhat the overall speeds.

[antonis]

I don't think you'll get a steady oscilllation from the circuit if you use larger than 100k (+ the small stopper resistor) as the rate pot.

Probably you're right, Duckie..
(I never tried such a pot value..)

250k Pot was a theoretical recomendation for "simulating" the original Rate width with the 470nF caps

After all, the guy is in a hurry to test it..

im going on vacation in 2 days and just wanted to finish and play with this before i left. Im to impatient to wait on tayda shipping,

[GGBB]

Those caps don't have to be film - you can also use MLCC - will avoid some bulk.

[antonis]

Those caps don't have to be film

Also NP Electros work just fine..

My son's EA trem works for more than 2 years with a combination of 1 Electro / 1 Film / 1 Poly-something (maybe PPS)

[Jdansti]

Those caps don't have to be film - you can also use MLCC - will avoid some bulk.

I've never used MLCCs. How do you recommend using them on a strip board when the leads need to be varying lengths? Attach leads to them?

[GGBB]

I have some MLCCs with long leads - I think they are from tape reels. But they do come in short lead ones as well.

[Jdansti]

I have some MLCCs with long leads - I think they are from tape reels. But they do come in short lead ones as well.

Ah. That's good to know. I thought they were surface mount.

[GGBB]

Ah. That's good to know. I thought they were surface mount.

I forgot all about SMD - yes those would be tricky to use on vero! 

You can also get axial through-hole MLCCs which would be ideal for vero I think.