hmm.. not sure, but should that matter? they're both the same chip.
and since the 47n and 10r are in series, does it matter which chip each goes to?

thanks Phil.. pretty sure I oriented the LEDs correctly as the both light up, and I also tested them with a 9V battery (and a 3K9 resistor) to get the polarity correct.


the power section seems pretty simple, but you're right in that I may well have goofed.. think I'll grab the datasheet and ensure I've got things within spec.

alright.. so pretty much a copy and paste from FSB (am a member there too) but thought it may be useful here, and also someone here may be able to help too..

I built this using the original (reversed) file, so turned my ICs inside out ( ) and got nothing, but the lm386 got warm

so I scored some more lm386 and started again with my own layout... built it and got nothing.. no sound at all..

I made the preamp and power amp modular.. easier to troubleshoot, and if I want I can swap the power amp out for something bigger maybe

the lm386 in the power amp are both getting pretty hot.. not melting yet, but I've not left it on very long cos I think they will if I leave it too long..

so, I disconnected the power amp and put the preamp into my ruby. I got a farty sound and only on full gain..
audio trace got it to the first opamp with good signal as far as pin6
as of pin 7 it was the awful farty sound.. kind of like a badly biased fet.. so I pulled out the LEDs and boom.. works awesome..
so a) do I need the LEDs in there (remembering I have zero theory knowledge so if they're vital, then .. um.. :blackeye )
and b) why would the LEDs cause an issue?
I noted that whilst they're both 3mm red LED, one is physically slightly larger than the other (maybe 0.5mm? but still nowhere near a 5mm LED).

thanks in advance

oh.. and layout and PCB are attached if anyone wants it, but bear in mind the power amp is as yet unverified and the preamp sounds like poop with the LEDs I had in there

ha ha.. so result correct, but assumption wrong... thanks very much  :tu:

oh.. one more thing.. am I right in assuming that the 1W 10R is effectively just a sort of dummy load? I don't have (and neither does my local electronics store) a 10R 1W, but they had 8R2 1W.. so if it's a dummy load then that should do, right?..

also guessing I could stick an 8 ohm speaker in there?

thought/hoped that was the case.. thanks :dbtu:
and yup.. everything else about the project seemed so "right" so I just assumed it'd be the right way round.. might do my own layout for it later on anyway and correct it there.

sorry for the dredge, but I'm starting to build this (btw, project file is attached.. if that is a problem, my apologies to the mods.. I"m new here :tu:).
what I don't know is the resistors need to be a certain wattage or not.
I started building it with 1/4W resistors, but the legs don't fit to the holes 'quite right' which got me wondering if I should have been using 1/2W ones (it looks like they would fit better).

the only resistor I can see which IDs a resistor wattage is the 10R from pin5 of the 2nd 386 chip.

also worth noting that the project file PCB needs reversing.. I found that after I etched mine

Quote from: newbiediy on April 26, 2012, 10:41:05 PM
I'm using the schematic at the FAQ section of runoffgroove.com. Sorry I can't give you direct link, I'm replying from my cellphone. It's very simple, really. Connect a 10 ohms resistor from jack's ground to speaker out negative.
But instead of 10 ohms, I use 220 ohms/2w because it's still too loud for me. Works for me, but I don't know if it's technically correct.
Use plastic socket. It needs to be floating. Grounding it will make VERY loud hum.
You can wire it so when you insert headphone jack, it will break the connection with the speaker.
Don't expect too high. This is the simplest way. The sound will be a bit dull. A cab sim will do better.

Hopefully this helps.

that actually helps heaps..  it's kind of what I was thinking of doing, but it's good to know the additional impedance may be useful (which is really what I was most concerned about). I may just put the 8Ω resistor in there and maybe a 250Ω pot as well so I could have a separate headphone volume.. thanks a heap.. that's very cool. :tu:

bit of a dredge sorry. just wondering how you added the headphone out to the little rebel?
thinking about etching one of these this weekend but keen to add headphone jack. thanks for any advice (schematic?) you can offer.