CHEEZOR wrote:I just got one of these because it was pretty cheap and I knew there were folks (at least one) here that are interested in the circuit. I don't have time to trace it out, but I have some pics that may make the process pretty simple. If there are any questions about values then just ask me and I'll get back to you as soon as possible.
CHEEZOR wrote:I found the list I made.
Parts that are labeled:
1002 = 10K
1004 = 1M
2001 = 2K
4992 = 49.9K
4993 = 499K
Op amp text (as best as I can read):
Line 1: OP191G
Line 2: #0809
Line 3: M3930
I think the part name is the first line since that is the google search which brings up the most Op Amp related results. The other parts are unmarked. The pot is probably marked and Im assuming that is 25K like all the other EMG pots, but I would have to double check to be sure and I dont know where I put the damn thing at the moment.
I just ran across this: http://freestompboxes.org/viewtopic.php?f=3&t=15541 which is probably very similar. Doesn't look exact (just from the number of caps), but probably still close.
askwho69 wrote:Nice one guys, i was looking for this one.. PA2 has white noise on it... they said AB is better that pa2... does anyone agree with that? i schematic is better for comparison does anyone write down the schematic?
askwho69 wrote:I want to draw the schematics but can you please clarify this one?
I wrote some question if you zoom the picture
The question mark - the 1M connection to +9 and negative for 4.5 biasing
in order to read a schematic,you need to be able to understand an opamp amplifier,in this case a non inverting one,with a +20 dB gain,nothing more than your average text book/datasheet application.irek81 wrote:Anybody has a proper schematic for afterburner? I do not know how to connect OP191. Anyone did that and it works?
i did some homework since this is a basic circuit and could be useful to me also.joebot101 wrote:I'm amazed no one has made a kit for this yet...
I have been wanting to make one fo these for aaaages.
I am glad this thread has sprung up, nice one guy XD
Quick question, does anyone have a PCB layout diagram... There are a few on here, but they aren't very clear.
Ideally, something I can just take and use right off.
Something like that would be great XD
the only errors are that V+ goes to pin7 and signal out is on pin 6,but that is not important now,its already fixed in my layout,i was just asking if its ok in dimensions,type and layout of components,then i can give the layout.phatt wrote:Hi alexradium,
I can't see how that pcb could work as pin 1 & 5 are not connected to anything?
Also those 1meg voltage dividers for the offset bias are not ideal.
If running from a 9 volt battery then a 10k/10k divider gives half voltage and then 1 meg to +input.
In the case of input on the inverting input you don't need the bias just a cap as the positive input is already DC referenced.
As a rule the positive input of most opamps need a DC path to ground.
Better minds here might explain it better.
If you wish I can draw up a schematic for you to work from.
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