help modding a tremolo design

[saxtim]

I built the following tremolo from a kit a while back and I really like the sound:

http://www.geocities.com/mejafu/schematic.jpg

The kit however came in a box that is sorta like a half rack space, with the controls on the side, not the top, and it's ABS plastic.  I'd like to make a stompbox version with true bypass, but I'm not sure exactly what to do as there are a couple of things I think will need changing.  Can anyone help me with the following:

Firstly - will this run on 9V or will it need 12VDC?

Secondly the power supply - I'm going to remove the LED and switch here, as I'll have an indicator LED with a 3PDT switch for true bypass.  I'll need to remove the 2.2k resistor before the LED as well right?  Also will I need those 3 caps there - If i only had say the 100uf going to ground would this suffice? What about the Zener diode (think that is what it is) Is the truely needed?

Thirdly LED 2/3 on the schematic and switch 2 - switch 2 turns the effect on and off - I plan to remove this and have the effect permantely on (I'm not sure if the switch should be permantely opened or closed though?)  Also what do I do with the Footswitch jack - can I just remove that and the circuit will still operate?

Thanks!!
tim

[Shahin]

When I went to your link, there was nothing there.

Shahin

[ErikMiller]

Not found....

[p1_ind]

copy the link, open a window, then paste the link, then it should open.

Adam

[analogguru]

1.) it should run on 9 VDC, maybe you have to reduce the value of the 4k7 between Q1 and LED1 to 3k3 or even 2k2.
Recommended to use for LED1 a yellow one, CdS-LDRs are most sensitive in this spectrum
2.) you can remove the 2k2 resistor befor the LED, but you must not.
3.) the other 2 caps (10µF) are recommende to have in the circuit as far as possible to the supply pins of every Op-amp
4.) There is no Zener Diode, only a 1A Diode D1, which is there to protect the circuit against reverse polarity, if you take the risk, to destroy the unit in the case of reverse polaritiy, you can ommit the diode
5.) LED 2 and 3 are only for displaying the speed of the tremolo... not needed.
6.) Footswitch jack is in paralell with S2, you can ommit both.
7.) keep the switch permanently open for operation

good luck, analogguru

[saxtim]

analogguru, thanks for the info.

A couple of things:

2.) you can remove the 2k2 resistor befor the LED, but you must not.

I don't follow this - I basically wanted to remove the LED because I was going to have an indicator LED running of a 3PDT switch when I wire the effect with true bypass.  This would make the LED in the power supply uneeded, besides I intend to remove the power switch as well, meaning that if I left that LED in it would always be on.  

5.) LED 2 and 3 are only for displaying the speed of the tremolo... not needed.
6.) Footswitch jack is in paralell with S2, you can ommit both. 7.) keep the switch permanently open for operation

Ok, so does this mean that I go from pin 7 of IC2b into the 2k2 resistor and then to VCC/2 (leaving out the LEDs)?  Do I also connect the 220k resistor (that was originally connected to Switch 2) directly to VCC/2 as well?

Recommended to use for LED1 a yellow one, CdS-LDRs are most sensitive in this spectrum

The orginal kit i made came with a high brigthness LED - i've got the part number so I'll get another one of those.

thanks again

tim

[saxtim]

made a mistake - the 220k resistor should go to pin 2 of the depth pot, not to VCC/2 right?

tim

[gez]

I don't follow this - I basically wanted to remove the LED because I was going to have an indicator LED running of a 3PDT switch when I wire the effect with true bypass.  This would make the LED in the power supply uneeded, besides I intend to remove the power switch as well, meaning that if I left that LED in it would always be on.

Yeah, get rid of the 2k2 as well if you're ditching the LED - it's superfluous.

Ok, so does this mean that I go from pin 7 of IC2b into the 2k2 resistor and then to VCC/2 (leaving out the LEDs)?  Do I also connect the 220k resistor (that was originally connected to Switch 2) directly to VCC/2 as well?

Probably best to leave the 2k2 coming off pin 7 in there, it forms a divider with the depth pot as well as limiting current to the LEDs, so it's probably been factored into the equation.  The 220k should connect to the wiper of the depth pot.

If you can, breadboard the circuit first.  You don't have to solder up any of the components (you can just make amendments to the original circuit), but it will answer a lot of your questions and save you a lot of headaches.  For one thing you can see if you can get away with loosing the 10u caps.  Also, ditching that 2k2 off pin 7 might give more depth?  Who knows? - that's the beauty of breadboards!