Super little gem MKII, need help!

[ochoco]

Hello! I found this schematic and is VERY interested in making it!
(source: http://www.diystompboxes.com/smfforum/index.php?topic=61795.0)



But I see quite a few capacitors and resisters missing the prefixes and I have very little knowledge about actual electronic...

And also, I got few more questions about this schematic.
1. if I want to add a blue LED for the power on/off indicator, which resister value do i have to use it? (for 9V battery situation)
2. will I be able to plug headphone/earphone straight to speaker portion of this circuit?
3. can I plug this amp straight to an audio interface to record the sound of it?
4. do I put diode for circuit protection on + side? or - side?
5. If i want to supply power to this circuit with 9v wall adapter, will 0.5A be enough? or will it be too much?

I know this is quite alot of questions but I'd really appreciate you guys help!

PS. I live in Canada, BC... Is there good and cheap electronic component seller?

[antonis]

Hellow you too..!! 

<I see quite a few capacitors and resisters missing the prefixes>
I can't see any resistor out of E12 series..
For caps of 250p & 0.05 you can freely pass to 220pF & 47nF..

1. Depending of the brightness of your taste, try a resistor around 5k6 Ohms..

2. It depends on headphone/earphone resistance (your Output power shouldn't be greater than head/ear phone's one..)

3. See above..

4. On + side (in case of series diode - preferably a Schottky one) or between + and - sides (in case of parallel shunting) - (watch for proper polarity orientation..!!)

5. Negleting J201, MPF102 & LM386 current consumption, you will need a power supply a little greater than your speaker power...
(there isn't anything like "too much" on power supplies - from the point of potential circuit damage..)

[duck_arse]

also hello, ochoco.

I always grump about something: this time, it's "I wish people wouldn't use 'A for audio' and 'L for linear' when marking their pots". "A" denotes log, and "B" denotes linear, and "C" is for reverse-log, and "W" is for tubescreamers.

however, to your quest. capacitors marked only with "p" or "n", simply add "F" and they will be sensible. same goes for "u" or it's Greek equivalent. so, pF, nF, uF. the cap in the top line marked simply "100" will be an electrolytic, 100uF, as it is a power supply bypass.

capacitors special case - there is a cap marked "0.022" (and another marked "0.05"). this notation is generally assumed as 0.022 microfarads, or uF. it is EXACTLY the same value as the cap marked 22n, ie 22 nanofarads = 22,000 picofarads = 0.022 microfarads.

resistors - we mainly just drop the omega symbol (or it's Greek equiv ....), so M for Mega, k for kilo, R for just plain ohms, and m for milli. please note the difference between "M" and "m". there is a resistor shown marked "10", this notation is generally understood to mean 10 Ohms, or 10R.

and: you can replace the decimal point in a value (any value) ie 6.8nF, with the multiplier instead eg 6n8. we generally then drop the unit as well, so no F.

I hope some of this helps.

[George Moore]

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  for the led you can start with say 3k3 to be totally on the safe side with the current through that diode.
  This method works wherever you want to make variable resistor to find the R value you like so a fixed resistor of that value can be chosen.
  starting with a 5k pot + 1k resistor and diode in series, creating a variable resistance circuit to test LED brightness, providing an adjustable R range between 1k and 6k. Apply your low voltage supply and adjust to taste, not sure every LED will survive the current at 1k...just adjust from dim setting [6k] until pretty bright, measure that resisance, then choose a fixed resistor close to that value...install where the VR test circuit found the preferred value.