PUNCH - 1W amplifier

[shrike88]

Having some issues. Thoughts?

http://youtu.be/pM4Z-XmG0TE

EDIT: I should also note that I get no sound at all from the guitar as well. I'm almost curious if the 2N5457 is dead. Not sure how I would test this anyways.

[shrike88]

Update: After rebuilding the circuit several times I've concluded I got a batch of fried ICs. The characteristics and noises (or lack thereof) change with each one I put in (I socketed the IC). I'll need to order more and hope they come in sometime soon.

[chromesphere]

Hi Shrike, you can fry the chip if you connect things up incorrectly.  Make sure you aren't shorting the output.  Minus on the output is not the same as circuit ground, just in case you weren't aware of that (got me first time ).  If the chip is getting hot, something is wrong with your build.  Someone stated earlier in this thread that the tda7052 is designed for 6vThey may get warm but none I have built have been 'hot'.  I haven't had issues with supplying the TDA7052 with 9v's before.  The datasheet rates the chip at a maximum of 18v from memory.

[shrike88]

I definitely have the speaker isolated, (Out + and - to the respective terminals on the speaker). I double and triple checked the circuits and there was no shorts. I multimetered all the connections and wasn't able to isolate the issue. I had five 7052a ICs, and each gave a different characteristic when plugged in. I had popping (as in the video) in different ranges and volumes. Another had no sound output. I unintentionally shorted one with a loose wire in testing (that gave off lots of smoke ). Regardless, I'll need to order more in now. The trick is sourcing them. The last batch I got off ebay since I can't seem to locate any online stores that carry it.

[Elijah-Baley]

My first building has been a Smokey Amp, and it was correct, but the output was very low. With a new alkaline battery the IC warm up within few seconds. I built it reverse! Everything was ok, but this "detail".
Maybe you are not fool like me. 

PS But are you using a pcb?

I don't know if it can help, but... Did you have connect it just with your Peavey amp?

[Lurco]

slight reminder, that the 7052 is different from the 7052A

http://media.digikey.com/pdf/Data%20Sheets/NXP%20PDFs/TDA7052_CNV_2.pdf
http://www.nxp.com/documents/data_sheet/TDA7052A_AT.pdf

[Elijah-Baley]

[...]
i would not connect it to the return [...] it may not harm anything , it may even sound ok , but it is not the proper method as you would be feeding the punch circuit into the other ones power amp . it also COULD damage something if it was cranked , etc ... not sure .

I remember that my amp have a "cd input", it is an 3,5mm jack input. I used it sometimes to connect my computer, or my mp3 player.
Could I connect my punch amp (when I wll build it) in this kind of input?

In the manual of the amp:
CD INPUT: "Use this 1/8" stereo mini jack to connect the output from a CD player, MP3 player, laptop, etc., to the amplifier.
The signal at this jack is summed into a mono signal, which is sent to the internal power amp circuit. Use the output level control for the signal source to adjust the signal for the proper mix with your guitar."

Could the punch amp work well and correctly without damage?

[bool]

One word: NO.

Mini-amps based on a LM386 (or any similar non-bridged chips), on the other hand, would most probably work just fine.

[Elijah-Baley]

I'm sorry, if I got it.
Could I connect to input cd of my amp a Smokey Amp, but no the Punch Amp?  

[bool]

One word: YES

Unless you "mod" the Punch amp by adding a cap-resistor section that would block the DC component to reach your inputs and possibly cause some harm. (So connecting a cap to either a pin 5 or 8 and add a resistor to ground to bleed the DC - and taking the "cd-out" from this resistor ... and of course ground).

It's quite simple when you think about it actually.

[Elijah-Baley]

Not so simple for me. 
But thank you! 

[bool]

Just add a cap to ..say, pin-5 of the TDA7052, in the same manner that you would do it with a 386 chipamp. 47uF would be more than enough, perhaps 10-22uF would be better.

Say, like here (but do it with the TDA7052 in the Punch amplifier):
http://www.beavisaudio.com/projects/NoisyCricket/oldpics/SmokeyTone.gif

Instead of a speaker, connect a resistor (or a pot), say 1K ..or even 10K, and this is going to be your "cd-out". You will most likely have to pad it down, since it's going to be too hot for a cd-input, so using a potentiometer instead of a simple resistor wold be even better idea.

Simple enough?

[Elijah-Baley]

OK, I got it better, now. Thanks! 

Damn! I use the stripboards for my circuit, and I cut the veroboard for the punch amp two days ago, while I'm waiting my package with the material. 
http://parasitstudio.weebly.com/stripboard-layouts/chime-amp-punch-amp-v2.

Meanwhile, I'm studing another thing. I don't got it well though I found some schematic. Have the speaker and the output jack. Actually, my Smokey Amp has just a little speaker (I'm waiting a new one from Tayda).

I want this kind of solution (speaker+output jack) especially for the punch amp. Maybe later I could buy an 8" speaker.

[Elijah-Baley]

I soldered all components on the board using a veroboard layout. 
About the "cap-resistor section mod" I'm letting it go for the moment. The board was cut yet. I could use a second board, but in the box I bought could be not space enough.

There's something not clear to me. Could I use an open frame jack for the input?
And for the output I have an amp style jack, with switch lugs. If I explain well, with this output jack I want to exclude the speaker on board when I connect an external cabinet.
I'm studying the wiring.

Thank you!

[Elijah-Baley]

Hi guys.
I built the circuit of the punch amp using a stripboard, schematic is the same of chime amp by chromesphere.
I did just a modify: I moved the volume pot, I inserted it before the input of the board.
I this way I have more volume (I tested it with a 8" speaker).

[arijit1035]

Hello,
First of all i would like to thank you for the punch amp diy. After hearing the amp on youtube have decided this amp would be a good start for a first time project. However i couldn't mange to get the mpf 102, my local store has got a 2n5484 jfet (www.datasheetcatalog.com/datasheets_pdf/2/N/5/4/2N5484.shtml) and the guy said it was same as a mpf 102. My doubt is regarding the jfet, will it work? or will i have to change some resistance, also what is the polarity of the 1u capacitor in the circuit (my 1u capacitor is polarised).
P.S. I am a noob regarding these things please help me. Excuse my english.

[tca]

^ The 2n5484 will work nicely.

The + of the 1uF cap goes into the TDA7052 input.

Cheers.

[arijit1035]

hello, i finally built the amp but when i connect the 9v battery it is draining fast like in 20 sec.... and while it drains the volume keeps getting low till it drains completely. I can connect the battery after some mins and it works again for 20 sec. i also checked all the terminals for any short circuit but found none now i have no idea what is going on! help please. 

[tca]

Check the speaker connections! It should be isolated from ground, see schematic.

P.S.
Some pics would help!

[arijit1035]

I am testing it with a headphone using i 3.5mm female jack... Anyways i will post some pics tomorrow... Also when i tested it with a 9v power adapter the amp was working without any decrease in volume but it generated a loud hum...