My New Super Mini 14w-32w practice amp!! Cheap and easy to build!!

[Minion]

Here"s another Update...I did a bit of a redesign of the amp ,I added another gain stage and added 3 sets of switchable diodes...I built the amp yesterday but a 32w version this time and I am playing through a 12in 60w Yahama Instrument speaker and useign an 18,0,18 50vA Torroid ...the results are outstanding, sounds even better than the other version and its Way louder.....

Here"s the Layout for the new version....



The only thing that is different is that there is another Gain stage and it uses a dual opa as opposed to a single and the tone controll has been moved to after the second gain stage and the option for more switchable diodes....

If anyone is interested in the PCB design let me Know and I"ll send it to you ,I just have a few touch up to do on it....

Cheers

[dschwartz]

hey that looks great!!

this thread made me resume my stereo tda2050 amp project i left behind last year.. with a 2 amp 12+12V xformer..
i remember i just kept overheating the xformer and the voltage dropped to almost 0 volts..i couldnt find the short..

till i realized that the tab of the chips are internally connected to -V.. the data sheet said is no problem to connect the heatsink tio ground!!!! yeah, they forgot to say "if u are using single supply".. i was shorting the hell out of the xformer and chip..

i re-started the project by isolating the chassis from the chip tab..  the voltage dropped from +-18V unloaded to +-11V on turn on.. and the heatsink was really hot after like 15 seconds..its possible that i blew the chip up due to previous shortings??

i´m going to design a pretty nice practice amp with 2 2050 in stereo/parallel..with stereo fx loop (power amp in), and a nice fet-based preamp at 15V regulated..

what do you reccommend? single or split supply?

[Minion]

Yes there is a chance that you may have fried the chip...it does have short curcuit protection but I"m sure it doesn"t protect the chip from repeated long term shorts....

I would recomend a dual supply so you don"t have to use a Big output cap....

If you need a power amp PCB design for any of the TDA Chips or other chips like the TDA7293 (100w) or the LM3886/3875 (60w) then let me know and I have PCB designs for these chips as well as the TDA2030/40/50 chips....I also have a PCB design for a single supply TDA20** chip with a discrete output stage useing High power NPN/PNP Transistors ,This increases the output current and let you drive lower impedance loads.....

Here is the PCB design for the Newest version of my Guitar amp (I just have to think up a name for it now)...



I believe the Connections with pots and switches should be pretty self explanitory but if anyone needs clarification let me know...

Cheers

PS: the PCB is 3.825in x 2.6 in....

[tranceracer]

If you dont mind me asking, Where did you get the torroid from and what are the specs on it.

[Minion]

Hi, the Torroid that I used for the TDA2050 chip was a 18v,0v,18v 50 vA (120v primary) for the other chips you should use a lower Voltage transformer (12v,0v,12v 30vA for the TDA2030 and a 14v,0v,14v 30vA-50vA for the TDA2040 and LM1875)...You don"t have to use a torriod ,and EI will work just as well I just used the torroid because I had it laying arround....

I get my Transformers from a Variety of sources and usually free or close to it...last year I was working on a Design that i was going to market so i contacted a bunch of transformer Makers and asked for free samples and I recieved quite a few Torroids for free this way but my Financial backer for the project left me hanging so i had a bunch of Transformers laying arround....I also go looking at the Salvation army and Thrift stores looking for good deals on equipment...I got a Busted Logitech 5.1 system for $8 last week and it came with 6 TDA7293 chips and a 500Va 30v,0v,30 torroid in it and also a 10in 200w sub, I also recently found a cheapo 5.1 system in the Garbage at the Brick that has 2 TDA2050 chips and 6 TDA2030 chips and a 14v,0v,14v 300vA Toroid in it.....

If you are looking to Buy one look on e-bay, or go scroungeing at thrift stores....

Cheers

[dschwartz]

men i love recycling stuff, i have tons of parts, (most of them unidentified semiconductors) taken for disposed pcb boards. it´s a lot of fun to find something valuable for free!, like xformers, a lot of poliprop caps, some electros (those that look fine), zener diodes, rectifiers..
sometimes is hard work to take out the parts, but is a lot of fun anyway..

[ambulancevoice]

any chance for a schematic on the updated one?

[Minion]

any chance for a schematic on the updated one?

I don"t have one right now so I"ll have to find time to make one up....It is exactly the same as the first one accept that there is another Gain stage which exactly the same as the first gain stage but has a Gain of 10x (10k and 100k feedback resistors, could be raised to 10k and 220k) and the tone controll this time is a 100K with a 0.01uF cap ,but other than that it is exactly the same as the first....

I"ll try to make some time to make up a schematic later today.....


Cheers

[earthtonesaudio]

men i love recycling stuff, i have tons of parts, (most of them unidentified semiconductors) taken for disposed pcb boards. it´s a lot of fun to find something valuable for free!, like xformers, a lot of poliprop caps, some electros (those that look fine), zener diodes, rectifiers..
sometimes is hard work to take out the parts, but is a lot of fun anyway..

+1

Also look to thrift stores for wall warts.  Often they're bundled with old answering machines, which have lots of cool stuff inside: speakers, switches, motors, etc.

[tranceracer]

Hi, the Torroid that I used for the TDA2050 chip was a 18v,0v,18v 50 vA (120v primary) for the other chips you should use a lower Voltage transformer (12v,0v,12v 30vA for the TDA2030 and a 14v,0v,14v 30vA-50vA for the TDA2040 and LM1875)...You don"t have to use a torriod ,and EI will work just as well I just used the torroid because I had it laying arround....

I get my Transformers from a Variety of sources and usually free or close to it...last year I was working on a Design that i was going to market so i contacted a bunch of transformer Makers and asked for free samples and I recieved quite a few Torroids for free this way but my Financial backer for the project left me hanging so i had a bunch of Transformers laying arround....I also go looking at the Salvation army and Thrift stores looking for good deals on equipment...I got a Busted Logitech 5.1 system for $8 last week and it came with 6 TDA7293 chips and a 500Va 30v,0v,30 torroid in it and also a 10in 200w sub, I also recently found a cheapo 5.1 system in the Garbage at the Brick that has 2 TDA2050 chips and 6 TDA2030 chips and a 14v,0v,14v 300vA Toroid in it.....

If you are looking to Buy one look on e-bay, or go scroungeing at thrift stores....

Cheers

Very cool!  I'm always salvaging xformers and have tons, but can never seem to score a torroid!  I'm always browsing the Thrift shops for project parts, containers and just picked up an old electric pot w/ variable heat to warm up my etchant.

[Minion]

I"ve been pretty lucky in finding things to use for parts ,I actually built both of these TDA amps with about 80%+ used parts ,The only things that weren"t used were the resistors ,Diodes and the PCB ..The Caps the Xformer,Jacks,Pots,Chassis,Speaker,wire,knobs,Heatsink were all recycled from various pieces of used and broken gear that I have accumulated and bought at thrift and junk stores ...My Garage is a mess but I have a lot of parts..LOL

Anyways here is a schematic of the revised version of the amp....




Cheers