Fryette Effects - SAS EF86 Overdrive [traced]
- diagrammatiks
- Solder Soldier
hey where did you buy that transformer?
who makes it?
who makes it?
- mat
- Breadboard Brother
Ok, so the bridge diodes will drop the voltage almost 2V's.. What about using the second (cascade) voltage doubler instead of the bridge rectifier and using a bigger resistor to drop the voltage to 9V and leave the regulator out ? I'll draw something later today.
Thanks again,
mat
Thanks again,
mat
ppluis0 wrote:Hi Mat,
I think that you can replace the 1 ohm resistor to another one of 56 or 68 ohms rated at 1/4 watt, and increase the size of the 47uF cap, maybe, to another 1000uF in order to have low ripple.
Considering that a single TL071 draws only 2.5 mA from the supply, the 56 or 68 ohm resistor of the RC cell result in almost 7.2 Vdc to feed this IC. In the datasheets I can`t find what is the lowest value reccommended to make this IC work reliably.
Perhaps any forum member can tell us about how to supply a TL0xx family chip.
Cheers,
Jose
- diagrammatiks
- Solder Soldier
man they have some nice toroids. wish there was something like those over here in the states.
for your power supply. you only need 8vdc for the op-amp.
just run a bridge rectifier and a big cap.
for your power supply. you only need 8vdc for the op-amp.
just run a bridge rectifier and a big cap.
- mat
- Breadboard Brother
Ok, bridge it will be then. Thanks !diagrammatiks wrote:man they have some nice toroids. wish there was something like those over here in the states.
for your power supply. you only need 8vdc for the op-amp.
just run a bridge rectifier and a big cap.
mat
- mat
- Breadboard Brother
Jose, I think I misread the value of the screen grid cap. Is it 100nF/400V instead 100uF/400V as I suggested ?mat wrote:Does the screen grid (pin1)100uF cap really have to be rated for 400V ? There is a 1M resistor between the 330V supply and the cap..
mat
Thanks,
mat
- mat
- Breadboard Brother
questions questions Would the http://www.datasheetdir.com/RB154+download be suitable for the rectifier for the 9V supply ? How about the HV rectifier ? Is it to small for that (rates from 50V to 1000V) ? Just want to be sure.
mat
mat
- ppluis0
- Diode Debunker
Yes. Is effectively a poly cap of 100 nF/400V, same as the coupling cap that connect pin 6 with the hot side of the volume pot.mat wrote:Jose, I think I misread the value of the screen grid cap. Is it 100nF/400V instead 100uF/400V as I suggested ?
Forgive me for having such poor handwriting ...
Cheers,
Jose
- ppluis0
- Diode Debunker
Hi Mat,
You need a bridge rectifier rated at 100 V/1 Amp for the low voltage supply, and another of 1000 V/1 Amp from the high voltage secondary.
Just think that the original unit have 4 x 1N4001 and 4 x 1N4007 at these positions.
Cheers again,
Jose
You need a bridge rectifier rated at 100 V/1 Amp for the low voltage supply, and another of 1000 V/1 Amp from the high voltage secondary.
Just think that the original unit have 4 x 1N4001 and 4 x 1N4007 at these positions.
Cheers again,
Jose
- mat
- Breadboard Brother
Thanks again Jose! One more (maybe the last) question is the voltage rate
of the 47uF cathode cap ? I only have a 47uF/25V and HUGE 47uF/450V ones..
mat
of the 47uF cathode cap ? I only have a 47uF/25V and HUGE 47uF/450V ones..
mat
ppluis0 wrote:Hi Mat,
You need a bridge rectifier rated at 100 V/1 Amp for the low voltage supply, and another of 1000 V/1 Amp from the high voltage secondary.
Just think that the original unit have 4 x 1N4001 and 4 x 1N4007 at these positions.
Cheers again,
Jose
- mat
- Breadboard Brother
Thanks ppluis0 for confirming the cathode cap.ppluis0 wrote:47 uF rated at 25 volts is fine.
Go ahead with this project !!!!!!!!!
Added today power switch + power light indicator and added also glue under and behind of the transformer. It is also kept in place with metal belt, so that is the last part to fall of from the box Two new pics:http://mattitee.kuvat.fi/kuvat/EF86over ... G_0566.jpg
Hope to finnish the main board tomorrow. Then I will make a small board for the IC and a bigger one for the power filter section. After that all it needs is wire
Thanks all !
- ppluis0
- Diode Debunker
Looks good to me, but the 1000 uF filter cap at the low voltage section must be of 2200 or more microfarads depending if you hear residual hum when you test this pedal.mat wrote:Could someone confirm the power section pic (lacks the 100k after last 22uF/450V) ?
In any case assign some space on the board if were neccesary increase the value of this filter.
Cheers,
Jose
- mat
- Breadboard Brother
Thanks Jose
Updated pic: http://mattitee.kuvat.fi/kuvat/EF86over ... sasPWR.png
mat
Updated pic: http://mattitee.kuvat.fi/kuvat/EF86over ... sasPWR.png
mat
ppluis0 wrote:Looks good to me, but the 1000 uF filter cap at the low voltage section must be of 2200 or more microfarads depending if you hear residual hum when you test this pedal.mat wrote:Could someone confirm the power section pic (lacks the 100k after last 22uF/450V) ?
In any case assign some space on the board if were neccesary increase the value of this filter.
Cheers,
Jose
- mat
- Breadboard Brother
The main circuit board is ready. Power supply board almost ready and the IC board is not ready yet.
One thing that came to my mind was that if the bias pot is 25k and not 20k is there a chance to outwear the tube too quickly for it to be biased too hot ?
mat
One thing that came to my mind was that if the bias pot is 25k and not 20k is there a chance to outwear the tube too quickly for it to be biased too hot ?
mat
- ppluis0
- Diode Debunker
Hi Mat,
Bear in mind that the values of these 3 pots were an guesstimate due we never seen the original ones.
Nevertheless you can put a resistor across the extreme terminals of the bias potentiometer, say 100 K and you will have the same bias voltage range as if you use a 20 K pot.
Perhaps is a better idea start paralleling your 25 K pot with a lower value (56 or 68 K ?), to see what bias range you have and avoid the risk of damage an expensive EF86...
Cheers,
Jose
Bear in mind that the values of these 3 pots were an guesstimate due we never seen the original ones.
Nevertheless you can put a resistor across the extreme terminals of the bias potentiometer, say 100 K and you will have the same bias voltage range as if you use a 20 K pot.
Perhaps is a better idea start paralleling your 25 K pot with a lower value (56 or 68 K ?), to see what bias range you have and avoid the risk of damage an expensive EF86...
Cheers,
Jose