Search found 54 matches

by poiureza
04 Dec 2018, 23:41
Forum: Pedal Debugging & Troubleshooting Support
Topic: proco YDR with eldzsi mod broke down ... more or less [SOLVED]
Replies: 3
Views: 967

Re: proco YDR with eldzsi mod broke down ... more or less [SOLVED]

After much trial and error the culprit was a defective distortion pot I have yet to open it but it seems half of the track is shorted, probably some metallic particle moving around. Pot swapped and my favorite pedal works like a charm again. And FWIW the 2.2V reading at the input was again a wannabe...
by poiureza
02 Dec 2018, 22:24
Forum: Pedal Debugging & Troubleshooting Support
Topic: proco YDR with eldzsi mod broke down ... more or less [SOLVED]
Replies: 3
Views: 967

Re: proco YDR with eldzsi mod broke down ... more or less [SOLVED]

Scrape my previous post, the input jack was no connected, thus battery ground was open. I still haven't found where exactly the problem comes from. I removed the chip and checked the voltage divider at the input again with a 9.24V battery. I attached a pic of a schematic I found on the web that look...
by poiureza
21 Nov 2018, 20:16
Forum: Pedal Debugging & Troubleshooting Support
Topic: proco YDR with eldzsi mod broke down ... more or less [SOLVED]
Replies: 3
Views: 967

Re: proco YDR with eldzsi mod broke down ... more or less [SOLVED]

I measure ~8V instead of 4.5V at the chip input with a 9.3V battery, so the problem comes from the 100k/100k voltage divider. I also measure 9~ish volts at all resistor ends of the voltage divider, so it's probably a broken connection at the ground side of the ground resistor. Time to get the tinker...
by poiureza
20 Nov 2018, 21:11
Forum: Pedal Debugging & Troubleshooting Support
Topic: proco YDR with eldzsi mod broke down ... more or less [SOLVED]
Replies: 3
Views: 967

proco YDR with eldzsi mod broke down ... more or less [SOLVED]

Hi there, No DIY pedal but I have this modded YDR that I bought used some 5 or 6 years ago FWIW eldzsi mod seems to consist in a LED/Si diode 3-way selector switch instead of the stock Ge diodes. There's also a middle position, thus no clipping diode at all. And of course the obligatory Motoralo LM3...
by poiureza
06 Jun 2018, 12:43
Forum: Circuit Blocks
Topic: 2 Band Active EQ Comparison
Replies: 3
Views: 4370

Re: 2 Band Active EQ Comparison

You can change the center frequency without too much pain at the expense of unequal behavior left and right from the pot's 12 o'clock position. I've built the bottom one with different values and it works great ! The real question is (and I had that question too - thanks POTL :D ) : why is the botto...
by poiureza
27 Feb 2018, 12:37
Forum: Pedal Debugging & Troubleshooting Support
Topic: BYOC Ge Fuzz face fizzy and no sustain at high gain
Replies: 1
Views: 489

Re: BYOC Ge Fuzz face fizzy and no sustain at high gain

It looks like the bias gets off with full gain. Can you measure the Voltages at Q1 and Q2 at 7'oclock and 3'oclock gain settings ? What is your sun dial setting ? 2'oclock gives you 4.5V @Q2c with max or min gain setting ? You could always swap the 33k resistor for say 47k or 20k and see how it goes...
by poiureza
20 Feb 2018, 08:50
Forum: DIY Projects
Topic: Nocentelli's JFET boost with Baxandall [documentation]
Replies: 10
Views: 5226

Re: Nocentelli's JFET boost with Baxandall [documentation]

Thanks a lot

May I ask what makes a JFET "decent spec'd" ?
Is it a matter a resistance value ?
by poiureza
03 Feb 2018, 10:04
Forum: Pedal Debugging & Troubleshooting Support
Topic: Transform 5 indepedent inputs to XLR balanced
Replies: 5
Views: 901

Re: Transform 5 indepedent inputs to XLR balanced

Sorry I meant "6-way single throw rotary selector"
If you want to tune silently you'll need a double throw at least.

Not sure what you intend to do but you could also include an internal mixer and only have one XLR out ...
by poiureza
03 Feb 2018, 09:59
Forum: Pedal Debugging & Troubleshooting Support
Topic: Transform 5 indepedent inputs to XLR balanced
Replies: 5
Views: 901

Re: Transform 5 indepedent inputs to XLR balanced

Yes, the tuner thing won't work like this. I would put a single tuner on a side chain and tap it in with a switch when needed (a 6-way single pole rotary selector maybe to choose from the 5 channels + 1 position left free). That's the plan but you might probably need additional circuitry to make it ...
by poiureza
22 Jan 2018, 15:21
Forum: Parts & Tools Sourcing & Trading
Topic: Supplier for Germanium transistors ?
Replies: 9
Views: 5901

Re: Supplier for Germanium transistors ?

minifux1 on ebay. I'd stay clear from that german seller. I have yet to find a single useable transistor out of the dozens of different trannies I bought from him. I've had MUCH better results with russian transistors on eBay. Check for the MP series (MP40 is a better ac128) Eventually I'd suggest ...
by poiureza
09 Jan 2018, 15:57
Forum: Pedal Debugging & Troubleshooting Support
Topic: EHX Linear Power Booster clone buzzing problems
Replies: 4
Views: 1000

Re: EHX Linear Power Booster clone buzzing problems

This circuit is so simple, not much to go wrong. My guess would be a ground issue. How clean is the solder job ? no bridging ? Did you use solder flux ? Did you build it on vero ? and is it boxed ? You sure the vero isn't touching the metal chassis ? How did you connect the different grounds (input ...
by poiureza
11 Dec 2017, 14:08
Forum: Pedal Debugging & Troubleshooting Support
Topic: Debug on own Crybaby
Replies: 17
Views: 2262

Re: Debug on own Crybaby

No, I simply said that you should notice a difference with a 1k resistor instead of the stock 33k resistor. And you should probably not notice any difference with 68k or 100k instead of the stock 33k resistor. The variable Q circuit in the Dime wah does add series resistance which is detrimental to ...
by poiureza
07 Dec 2017, 13:02
Forum: Pedal Debugging & Troubleshooting Support
Topic: Debug on own Crybaby
Replies: 17
Views: 2262

Re: Debug on own Crybaby

Hey, still working on the wah I see ! As for your question, one explanation I see is that the resistor is in parallel with the inductor ESR : Say you typically have an inductor resistance of 200R and that 33k parallel resistor. Total = 198R 100k resistor in place of 33k will yield 199R instead : not...
by poiureza
06 Nov 2017, 21:05
Forum: Pedal Debugging & Troubleshooting Support
Topic: OP amps clipping way below rails
Replies: 10
Views: 1907

Re: OP amps clipping way below rails

Thanks again I'd really need to update the picture of my circuit. It has changed a lot since my second post were I added negative PS (so I have +16 and -8 volts) and DC offset the input signal to +4V. And I have an input cap and series resistor now ... Both 100K resistors are coming from a dual 100k...
by poiureza
03 Nov 2017, 22:32
Forum: Pedal Debugging & Troubleshooting Support
Topic: OP amps clipping way below rails
Replies: 10
Views: 1907

Re: OP amps clipping way below rails

Thank you for your input Phil. I must admit I'm a bit confused about what the cap to ground in the leg outside the FB loop does. Beside the eq'ing (though with 10uF it has almost no effect) it must do something else. For instance, if I remove it and connect the 3k3 direct to ground instead, the opam...
by poiureza
20 Oct 2017, 23:01
Forum: Pedal Debugging & Troubleshooting Support
Topic: OP amps clipping way below rails
Replies: 10
Views: 1907

Re: OP amps clipping way below rails

Sorry, "CN" was an attempt at a bad joke. I bought that chip from a chinese seller on eBay. And it actually says "TL072CP" No specific data sheet, I found the figures in the TL072 spec from TI http://www.ti.com/lit/gpn/tl072a I picked the 8V max peak output for Vcc=10V and KL=2ko...
by poiureza
09 Oct 2017, 19:05
Forum: Pedal Debugging & Troubleshooting Support
Topic: OP amps clipping way below rails
Replies: 10
Views: 1907

Re: OP amps clipping way below rails

Mmmmh ... that was the very first thing I did when the initial setup gave strange figures, but it made no difference at all. My understanding is that this DC path clamps the voltage at pin 3 to ground when no input is connected. It doesn't make any difference once a ground referenced signal is appli...
by poiureza
08 Oct 2017, 18:42
Forum: Pedal Debugging & Troubleshooting Support
Topic: OP amps clipping way below rails
Replies: 10
Views: 1907

Re: OP amps clipping way below rails

Some update I added positive voltage doubling from the 7660 chip : now I have +16V and -8V. I added a resistor network at the non-inverting input (2x 1M with ends connected to the +16V and -8V pins ) to bias the input at midrange i.e. 4V. Spice tells me that I have now a maximum clean output swing o...
by poiureza
07 Oct 2017, 21:44
Forum: Pedal Debugging & Troubleshooting Support
Topic: OP amps clipping way below rails
Replies: 10
Views: 1907

OP amps clipping way below rails

I made a very basic amplifier using a TL072CN ("CN" probably stands for "China" lol). 1.jpg I used a 7660 chip to double the voltage range : I get +8 and -8 volts out of it (measured) The Spice model predicts the same voltage values that I read on the scope. It also predicts that...