my 2nd "DIY" amp , the XAM

[petey twofinger]

a little larger , but i like the tone , i will add a distortion circuit to this eventually , on the second channel maybe . the amp board came out of a karoake machine i got super cheap at salvation army . the delay is modified for longer echo . this was a very fun / pretty simple project , a great idea for a beginner to get their feet wet , also , really cheap .

part one i talk , part 2 i play thru it .

http://www.youtube.com/watch?v=zczdqEMQHDk

http://www.youtube.com/watch?v=046PxdOjX-k

thanks for watching , any feedback is mucho gracias !

[joecool85]

Can't watch the video right now but plan to later.

Do you have any pics you can post up?

[petey twofinger]

honestly not of this project , the stuff i do videos for i usually dont take pics of , but thats a good point , i really should ! i learned a few things when i put this one together , and shared at least one cool trick in the video . i had fried a circuit the evening before so i threw this together to make myself feel better . speaking of massive failure :

lately i have been having awful luck with a 555 circuit , an oscillator , i have made 4 different boards from scratch , 2 different designs and they all suffer the same intermittent fail . well not really , it works for a minute then the pitch rises and it stops workin . my 4th board will be ready to test tomorrow , i have my fingers crossed (the 2 good ones) wish me luck !

dont give up on me yet , theres 3 more amp vids to come ! (they get better as i go , i swear)

[joecool85]

Thanks for sharing your projects Pete, they're quite interesting.  It's always good to see new ideas on how to do things.

[petey twofinger]

i didnt think i should make a thread like "post pics of your workspace" so ill just share these here . i do some smaller work , a lot of times , so i slapped this togther when my paki neighbors moved and threw out the cutting board and a lamp . i have been "improving" it as i go . it has a lil defumer fan with a p.s. and a switch .  i have a larger one on a foot switch thats like 3 feet away , i run that as well . i added florescent lighting today . the incandescent 100 watt was a bit too hott for summertime !



in this pic you can see the magnifying glass , sometimes i "bridge" connections , tough to see , for me anyway .



the whole thing ran me 5 bucks , for the fluorescent lamp , the rest is just scrap .  i think i am finished adding crap to this though . i dont want it to blow a fuse / burst into flames . i was kinda busy today , put in a window unit AC in the kids room . its HOT !  i am hoping that lil circuit in the picture works !

[joecool85]

No problem making a "show your workspace" thread.  I think we may have one here...or it might have been over at diystompboxes that I'm thinking of.

Nice small setup though.

[petey twofinger]

well that little circuit worked for a minute , then the pitch rose and it stopped producing sound !

this is the 4th board that failed in this chassis.  the chassis houses a cds cell , the 9volt batt clip , and the mini speaker (out of an lcd monitor) .

i tried a different 555 oscillator design on the 3rd try , it did the same thing . i bought some lm386n chips and made a square wave osc out of that but it was very quiet .

so i am going to test the components in the chassis again . try a different circuit design and pray . this thing has given more grief than just about anything i have put together . it getting tough on me . i have no i dea why all these circuits stop working after a minute , when the prototype model , the one i built first that took a minimal amount of time tyo slap together is solid as a rock , and the other 4 boards i took time on ,  work for a minute then fail .

i usually troubleshoot these boards for a few days , trying everything as i go , to no avail . i just cant undestand what is the problem ? so i rebuild the circuit / rebreadboard . the final test is the same , the unit fails , so i swap out the chassis mounted componats to the bread board and it works . rebuild board . same issue . new circuit design same chip + smae problem . super clean ultra perfect original version with all everything perfect = fails at 5 minutes , switch chips  , still fail .

everytime this happends i switch out the componants (cds , spk , batt clip) on the chasis to the breadboard , it works . hook up the pcb version to different cds / batt clip / spker it works , well last time it failed .

wfth ?

i have wasted so much time on this , and i need to move on . i am hoping that thru more extensive testing i will find a goofy cold joint in the chassis component , like the cds / batt connector . this would make me happy . the thing is the chassis is tiny , and i used tiny drill holes / hot glue to hold the cds and wire in place (its solered in there too) . and when i test those they come up good anyway . it seems easier at first to write off as a soldering error . ive tried swapping everything . many many configs of different p.s / regulated ps / batts  new , rechargable , etc . staring at it under magnification , continuity tests , jumpering , you name it i have tested/swapped  this board / components up and down . cant figure it out , eliminated every possible thing . works on bread board , soldered up nice in chassis , works for minute or so , quits . wait 10 minutes works .

anyone run into anything this demonic before ?

like i said i get good results untill i put it all together , then 1 minute 1 fail !

this is the circuit

http://www.dinofab.com/slidersynth.html

the mods i made are an output jack for audio (switching 1/th inch headphone) that comes off the main chip putpu . if you plug in a speaker it shuts off internal spk , and audio goes out to extrnl spk . then i changed the cap from a 2.2 to a 1uf for highr pitch . this cap has been switched/swapped with original value or many other values before , still same problem . switch chips it still is in geek mode . wierd works at first then shuts down , switch chip still wont work unless you let it ist 10 minutes then works well for a minute .

i tried a different design circuit it failed too .

http://img14.imageshack.us/img14/5848/onecdstheramin.jpg



this one did the same thing , so where should i look first to nail this problem .

ps dont let me discourage you from this circuit , its my personal favorite lil noisemaker . i play along with the incredible hulk tv show , and CHiPs (john and ponch ) . you can do the theme song , then do "folly" music parts , think sherwood shwartz mini vamps for folly points .  this thing has the most accurate control parameter as far as  a cds cell device can go , you really can play it more musically than other designs . try this thing , its awesome . the led in a tube with a cds cell on the end of it is amazingly playable , its tough at first but its more stable than any other method . its really cool . i could see making these sensor / emiter combos and have them pulg into all sorts of circuit bent devices for more accurate "musical" control . 

the first one i made copied dinos circuit , then i added an output jack for audio to switch off the speaker when you plug it in to an external spkr or amp . i also changed the cap value from a 2.2 to a 1uf , but that didnt make it fail in the breadboard version , and i swapped that out for the original value in the final mess for the original value 2.2 , and it still bit the big one .

what is going on here , brotha ?

i guess that really isnt fair , but i am hoping i can nail this down soon . i am starting to loose it here . anyone run into a case where a device works for a minute the it geeks ?

[joecool85]

Sounds like a definite issue with your chassis.  I've had this happen myself.  Works on breadboard, works on veroboard out of chassis, mount it up and it dies.  Could be a shorted output wire or something in the chassis.  Run over it real good, tear the chassis apart if you have to and re-do all wires and connections - not just solders.  That's probably the only way you'll fix it.

Good luck and keep your chin up, this happens to all of us. 

[petey twofinger]

i took the chassis , which houses the 9 volt batt clip , spkr , and cds cell , hooked that up to a breadboard , and ran it for an hour last night . this is at least the 6th time i have done this . i can not duplicate the failure unless the board is mounted on the chassis screws .

going to slap another new board together , with a different circuit this time , an fmims3 , and cross my fingers .

the chassis is tiny , and i used epoxy to build it so replacing the cds cell and spkr is impossible unless i destroy the chassis . i have another identical speaker and cds cells . so may have to just go ahead and make another chassis .

[joecool85]

i took the chassis , which houses the 9 volt batt clip , spkr , and cds cell , hooked that up to a breadboard , and ran it for an hour last night . this is at least the 6th time i have done this . i can not duplicate the failure unless the board is mounted on the chassis screws .

going to slap another new board together , with a different circuit this time , an fmims3 , and cross my fingers .

the chassis is tiny , and i used epoxy to build it so replacing the cds cell and spkr is impossible unless i destroy the chassis . i have another identical speaker and cds cells . so may have to just go ahead and make another chassis .

It could be when you tighten down the screws it is causing a short.

[petey twofinger]

 yea ! the lil project that couldnt finally worked !!!!

it turns out the fifth one was the charm . we celebrated with some garbage picked kirsten negale .

http://img694.imageshack.us/img694/2137 ... 40x480.jpg
http://img577.imageshack.us/img577/9858 ... 40x480.jpg
http://img690.imageshack.us/img690/7986 ... 40x480.jpg
http://img534.imageshack.us/img534/3703 ... 40x480.jpg

im so happy ! i can move on now . i have tons of *s!!t* to do ! i just wish i knew why the first four boards kept geekin out !

[petey twofinger]

bad links too !

http://img694.imageshack.us/img694/2137/sdc11602640x480.jpg

http://img577.imageshack.us/img577/9858/sdc11599640x480.jpg

http://img690.imageshack.us/img690/7986/sdc11600640x480.jpg

http://img534.imageshack.us/img534/3703/sdc11601640x480.jpg

[joecool85]

Glad you got it going!

[petey twofinger]

i know its  highly OT , but , i am gonna do a short video with this thing , ill throw a link up in here within the month . we are gonna be super busy for a while .

i cant tell you how happy i am !

finally .

[J M Fahey]

i cant tell you how happy i am !

We too.
Congratulations. :tu: