Here's a little project I recently completed.

The Lunatic Fuzz, aka DSOTM. (Dark Side of the Moon)
The pcb is from GuitarPCB.com  http://www.guitarpcb.com/

Just completed this... My second attempt at applying graphics to an effects box.

EDIT; PHOTO HOSTING SITE REMOVED ALL PICS THAT WERE EMBEDDED HERE.

I'll try adding them back in as attachments....

Another eBay acquisition. 

Here's pics of how it came to me.
This ones gonna need some work. 

Right out of the shipping box it was/is filthy!

In case it wasn't noticed...
I seem to have a weird affinity for these cheap/trashy/small/throw-away/old/SS practice amps.   <3)

I have about 8 of them now and the supply of reasonably priced units on fleabay seems to have dried up.
I wonder who could be responsible for that???  :lmao:
All I'm seeing now on thebay is guys that want a fortune just because it's "vintage" 




Gonna need a new rear panel for the speaker cab.
This one looks homemade.   




Speaker jack on the left. Tremolo and Reverb foot-switch jacks on the right.



Got a Radio Shack full range 8" with whizzer cone in the top location.

What is possibly??? one of the original speakers in the lower spot.

Gonna need some new speakers and a new baffle.

Perhaps some nice 10 inch units since I have to replace the baffle anyway.

Opinions on the ports?
Should I cut them on the new baffle or not bother?




To my surprise and delight... what appears to be the original schematic and parts list was tucked inside.      :dbtu:



Here is a scan of the original schematic. 
Probably the only one on the whole Intergoogle thing...  :lmao:

In the process of redrawing this to make it more readable. Will post that when I have it done.



More...

Looks like someone messed with the input jack wiring cuz on a quick glance it doesn't seem to match the schematic,
but other than that the amp looks relatively untouched. Yay!





I know I should make some changes to the mains wiring for safety reasons,
but the eBay seller said he powered it up to see if it worked so I just had to try it out.

Plugged it in and yeah, it works great!
Very clean even at full volume, albeit not very loud.
Practice amp bedroom level.
Tremolo and Reverb work ok.
Actually a very nice rich sounding SS amp.
Seems like lots of harmonics and "shimmer".   8|  :dbtu:

More...






Cheers!

EDIT; THE PICTURE HOSTING SERVICE I USED HAS SHUT DOWN AND REMOVED ALL PICS.

I will add them as attachments at the bottom of each page.


So I "acquired" this amp...  <3)

It had some issues and I could not find a schematic....

So I traced the 2 circuit boards and created schematics from that.

Probably the only schematics for this amp on the whole interweb...  :loco

It has power supply and power amp on one board,
and pre-amp board separate.

All component values are original as found on the boards.

EDIT: redraw of pre-amp schematic to make it easier to "read" 





On the power amp board there are 2 mystery components that look like capacitors but I can't get a reading with my cap tester.
They do give a resistance reading.

There are no markings at all on these parts.




They are marked on the power amp schematic as ? and 22R because they measure 22 ohms.
Right next to R3 and R4

Seems odd to me that they would put them in parallel with 20 ohm resistors.
Can anyone shed some light?








EDIT: Corrected pre-amp  and Power amp schematics.
Fixed reverb tank.
Added transistor types to pre-amp schem.
Added themistors to power amp schem.

I was rummaging through some old forgotten stuff and came across this old TSM Electronic kit.
I think I bought this at a surplus store some ages ago.
The instructions did not have a schematic, so I traced the board.
I "think" I got it right.

Near as I can tell, the input transistor buffers the signal to the LM386 which drives the "tank".. (and isn't that tank a cute little thing.  )
The tank measures approx 10cm X 2.5cm. It's like a tiny version of a real reverb tank with tiny coils and magnets and springs.
One of the springs is slightly heavier/thicker wire.

Looks like the recovery amp Q2 sends the wet signal to the resistive mixing network and P2 appears to be a "blend" control.

Can anyone see any possible errors in the schematic? Any insights on how well this might work?

I suppose I could solder it up and try it.... 

Any obvious areas for improvement?  I'm sure it is Lo-Fi at best though...  :lmao:

Greetings all!  Yet another small project to work on.

Building a small practice amp.

I have a small power amp kit, this one >>> http://www.canakit.com/20w-bridged-audio-amplifier-kit-CK193-UK193.html?gclid=CM_jme-qycUCFZSCaQod-QwANg

Using a Eminence 820H 4 ohm driver. Not very efficient but it's what I have.

Power supply recommended for the above kit is a regulated 18V single ended supply.

I have a suitable supply, so now working on making a 2 input (High & Low) preamp with just a simple tone control.

The attached schematic is what I have come up with so far...

See any mistakes, obvious errors?
Any suggestions for improvements?
Maybe an additional buffer after the Vol control?
(perhaps some diode clipping for the High Input?)

TIA!

Hello all,  long time away, now back with a new project.  :loco

Hoping the brain trust here can help. 

I bought this Chip amp. http://chipamp.com/product/lm3886dm/

Intent is to use each Chip amp and P/S board separately for 2 different guitar amp projects.

Project 1.
So far I have a basic pre-amp and 15-0-15 supply (see schem).

Seems to work ok. So far, so good.

Next is a Tremolo circuit, (see second schem) and this is where I'm having a bit of trouble.

I have a working LFO that has an awesome speed range from very sloooow to crazy fast.
The output is a nice triangle wave with +5V -5V peaks.

From this output I want to drive an LED, and have said LED with variable brightness, (this will be the "Depth" control for the tremolo).

The LFO is capable of driving an LED directly from the output of R7 to ground.
In fact it will drive 2 LED's in reverse parallel from R7 to gnd.
The LED's flash alternately.

I just can't figure out how to drive a single LED and have a nice smooth, wide range, variable brightness control (Depth) for the LED.
Goal is to have the LED range from completely off to max brightness.
The LED will be paired with a CdS photoresistor (all wrapped in heat shrink).

BTW I'm using a green LED, I don't have the specs but with my meter on diode check it measures 2.8 fwd drop.
Using green cuz I read on the interwebs that CdS cells are most sensitive to light in that range.

I have bread-boarded a couple of things (really, just stumbling around in the dark) using the LFO to drive a common NPN transistor, resistors and a pot, but none of my efforts have proved workable.

Is this even possible with a dual 15-0-15 supply?

Thanks for any help or hints!

Edit; OOPS maybe I put this topic in the wrong place?
Should be in Pre amps and Effects instead?

Mods please move if needed. Thanks!

I'm so stoked!!!  <3) I just had my latest pedal build featured on GuitarPCB.com! 

Here's the link...EDIT; link no good anymore, removed, see below...  http://www.guitar pcb.com/   This link with my pedal featured will prolly only be good for a few days ...

(In case anyone was wondering where I'd gotten to... I've been spending a lot of time building effects pedals) 

I still look in here every day though. Still some unfinished projects begging for attention.... 

Not sure where to put this. Mods please move if required.

I'm contemplating buying a vacuum desolder station and would like to see what other folks are using.

Seen some on eBay fairly cheap. As low as $75.00.

I don't want to spend more than about $150.00.

Anything decent for that price area?

This will only get occasional hobby use so no need for a $1000.00 + pro model.

Thanks for any suggestions!

So in my circuit newbishness I built the Trill Tremolo from MODKitsDiy.

http://www.modkitsdiy.com/pedal/trill_tremolo

Turns out they have a Mod for the Mod kit....       :cheesy: 

Actually more than one mod...

They have...

DC power jack add... Mod

LED add... Mod

Intensity control... Mod

(Ok, enough already, they see the bad humor) .... Did I say that out loud?

I've already done the DC jack and the Intensity control.
Waiting for a 3PDT stomp switch to get here so I can add the LED... but wait...
Why have a boring plain old glowing-not pulsing LED when you could have....
....a pulsing LED.

There is already an oscillator circuit right there!
Just need to tap into it somehow...

Here's the schematic for the Trem...

http://www.modkitsdiy.com/sites/modkitsdiy.com/files/product_files/the_trill_tremolo_schematic_1.pdf

I tried to interface an LED with a 2N3904 BJT but could not get it to work.

EDIT; I hooked onto the collector of Q3 in the trem circuit.

No matter what I did it would either load down the circuit and kill the oscillation, or the LED was so dim you could barely see it.

Ok, new plan, try a JFET. PF5102

The schematic attached below is what I came up with.

Can anyone tell me why/if this..
A. is a bad idea
B. won't work properly
C. has potential trouble spots
D. has circuit design errors

Also, where to connect to the 3PDT switch (when it gets here) to kill the LED at the same time as the effect.

I was thinking to put the switch on the 9V line going to the LED circuit.

If I were to put the switch on R1 of the LED circuit, it would kill the pulse but the LED would stay lit.

I have bread-boarded the LED circuit and clipped it into the Trem circuit at power, ground and the collector of Q3
it seems to work...
But I did not actually plug a guitar and amp in to try it.
EDIT; actually I have now plugged in a guitar and amp and the Trem still works, so far...

Thoughts? Opinions? Help? 

Thanks!

EDIT 2; Here is their plain old boring, non-pulsing LED add schematic.

http://www.modkitsdiy.com/sites/modkitsdiy.com/files/product_files/led_add_schematic2_2.pdf

Hello all, newb here... go easy on me  Here is a schematic I have generated after extensive searches failed to turn up anything usable.

I tediously/laboriously followed the board layout and made a drawing of all component placement and traces.
With that in hand I sat down and created the schematic in ExpressSCH. Took a couple tries but I think its good now.

Hoping someone can help with the crappy reverb sound I'm getting from this amp. Yeah, I know, it's a crappy little amp but I'd like to make it sound a bit better that it does right now. (Sentimental Value ya know?)

This amp actually has a pretty good deep sounding Tremolo tho the speed range is a bit narrow.

As you can see from the notes on the schem I have already made some changes as the amp was very quiet when I first got it.
Putting a jumper in place of R16 made the biggest difference in volume, but the already bad, tinny, feedback prone reverb got even worse.
I also replaced D2 with a new germanium diode that feeds the trem circuit and got a tiny increase in volume from that change as well.
I suspect the original diode was leaky.

I'm wondering if it's possible to replace the stock single spring piezo reverb tank with maybe the Belton Digi-Log module.

http://www.accutronicsreverb.com/

Might need to add a small driver/recovery board. I'm uncertain about what circuit would be needed to interface with the amp and where to tie in.
If you have looked at the schem you no doubt noticed the odd (at least to me) use of PNP transistors and the funky positive voltage on the chassis. Kinda weird compared to more modern designs.

I don't expect miracles but a bit more volume would be nice too.

Thanks for any and all reply's, help, advice, suggestions, ideas etc 

Edit: Oh ya, check the funky transformer phase splitter (at least I "think" that's what it is) to the "power amp" section.