Sarno Earth Drive
- sugarinthegourd
- Breadboard Brother
- RnFR
- Old Solderhand
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moved to REQUESTS FOLDER.
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Blog-APOCALYPSE AUDIO
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- sugarinthegourd
- Breadboard Brother
Here's a pic of the back of the board. 3 board-mounted pots, maybe an IC in the center. Looks like fairly low parts count. YATS?
- caspercody
- Resistor Ronker
Any updates on this?
- Kitrae
- Breadboard Brother
I did not photograph the other side when I reviewed it, but I can tell you is is TS based.
Kitrae - Muff junkie
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- Cub
- Cap Cooler
Thanks, Kit ! I half expected it to be TS based. Brad Sarno did well on this one.
Normally, I really don't like the sound of a Big Muff going into a Tube Screamer, but the clip you posted with your review sounds great.
Normally, I really don't like the sound of a Big Muff going into a Tube Screamer, but the clip you posted with your review sounds great.
I wish I were a chestnut tree, nourished by the sun.
With twigs and leaves and branches and conkers by the ton.
With twigs and leaves and branches and conkers by the ton.
I might know someone that took some gut shots of an EarthDrive they bought years ago...this same person might have done a full trace after getting pissed off that the diodes were gooped and the IC sanded. I was able to find the pictures and some of the parts values for now.
I do know the IC was eventually determined to be a 4558; the sanded one was put in a test circuit and had voltages measured at the various pins under several sets of conditions that matched pretty much exactly with a labeled 4558.
I do know the IC was eventually determined to be a 4558; the sanded one was put in a test circuit and had voltages measured at the various pins under several sets of conditions that matched pretty much exactly with a labeled 4558.
- Manfred
- Tube Twister
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I redrew the circuit diagram, so you can see the circuit structure better.
My guess for the IC are TL072 or CA3240 and for the germanium diodes 1N34A.
My guess for the IC are TL072 or CA3240 and for the germanium diodes 1N34A.
Last edited by Manfred on 19 Sep 2022, 09:50, edited 1 time in total.
I know a TL072 was tested and didn't measure in the same ballpark as the mystery IC; not sure about the CA3240. Also not sure about the exact testing methodology, whether it was a reliable way to make an informed guess, or anything else about that part really.
- mauman
- Resistor Ronker
Your DMM probably uses around 1mA for testing diodes, while the Peak used 4.29 mA. Diode forward voltage drop varies with current, and makes a curve that increases with increasing current. A reading of 241 mV @ 1 mA and 644 mV @ 4.3 mA would be in the normal range for Ge diodes.
- Manfred
- Tube Twister
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- Manfred
- Tube Twister
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I got a bunch of 1N60P Germanium diodes that look the same as the diode on your snapshot, also the readings are in the same range.GratefulEight wrote: ↑19 Sep 2022, 02:40 The Ge diode (clear DO-7 with 2 black stripes--see picture) that survived de-goop measured Vf = 0.644V, with a test current of 4.294mA on a Peak DCA55 tester; a standard DMM said 0.241V on diode test mode. Not sure why the discrepancy...leakage? Low DMM battery?
Reading: Vf=0,736V at 5,00mA
Last edited by Manfred on 19 Sep 2022, 15:51, edited 5 times in total.
- Nocentelli
- Tube Twister
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So essentially Paul Cochrane's Timmy, minus the bass pot but with half ge diodes?
modman wrote: ↑ Let's hope it's not a hit, because soldering up the same pedal everyday, is a sad life. It's that same ole devilish double bind again...
- Manfred
- Tube Twister
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In fact the same circuit structure, then what's the point of gooping components.Nocentelli wrote: ↑19 Sep 2022, 11:52 So essentially Paul Cochrane's Timmy, minus the bass pot but with half ge diodes?
The circuit copier fears nothing more than that his circuit is copied.