Hi guys and girls, I haven’t soldered for a long time but I’m planning to make a Tchula pedal, and I have a question about diodes.
There is on the circuit that I found a diode just after the arrival of the + (so I imagine that it is a protection diode against an unfortunate polarity inversion).
it is noted 1N5187, of course I don’t have one.
but would a 1N5817 (which I have) do the trick ? (plus there are only the middle digits reversed and it’s the same number 
)
or what other diode could do the job please ?
it’s a 9v circuit for guitar pedal
thanks in advance
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I think it’s just polarity protection and you could use the 1N5817. And maybe try a 1N4001? Can you post your schematic or a link please.
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The 1N5187 has a higher forward voltage, so there will be more considerable voltage, something the designers probably tried to avoid by using the 1N5817. I doubt that there will be a difference in the sound considering that the difference between the diodes is approx 0.4V, which is also the difference between a fresh 9V battery and actual 9V…
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Cheers, yup it’s just polarity protection. Use what you like.
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Thanks again 
or maybe put no diode at all ? (like my other diy modules or pedals)
If you’re powering this from a battery there are few chances that you will connect it backwards. Even then, you might just fry a couple cheap components. I wouldn’t worry about the diode. The crucial thing in the sound is the 2N5088 transistor (you need a high gain there, 2N3904 won’t do) and the clipping diodes (you need Shottky diodes there for the intended sound, but you can try others to taste…)
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I will bet you $7.56 it’s a typo for 1N5817. $7.56 being the price at Mouser for one (ONE!) 1N5187 diode.
The stripboard says all three diodes are 1N5187 but the schematic says the two clipping diodes are BAT46 ($0.34). BAT46 and 1N5817 ($0.23) are Schottkys while the 1N5187 isn’t.
I was going to cite a comparison of their forward voltages but you can’t really compare them: 1N5187 is 0.9 V (min) to 1.5 V (max), measured at 9 A; 1N5817 is 0.45 V at 1 A and 0.75 V at 3 A; BAT46 is 0.25 V at 0.1 mA, 0.45 V at 10 mA, and 1 V at 250 mA.
Agree you can omit the protection diode unless you really think you might connect the battery backwards somehow. For the clipping diodes, 1N5817 will clip harder than BAT46, but it’s up to you which you use.
(Given the probable typo, maybe mark that stripboard unverified…)
Also: At Lovepedal Tchula | MUSIC STORE professional it says:
The Tchula love pedal was developed at the request of Blues icon Josh Smith and combines two COT50s arranged in series in one housing.
so it looks like this isn’t really a Tchula schematic, there’s only one of anything.
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Thanks, yes i use BAT for clipping
I think Josh Smith have a special version, COT50 is another version of the Tchula (the original Love pedal Tchula schem in my post)
not really the same components values
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