Hi,
I have been working too much at uni to do much diyaudio but now summer is coming i am going to build an Ampslab C200.1
http://www.ampslab.com/c200qc.htm
I pretty much have all the bits necessary but i cant make PCB's. I am therefore going to have to use veroboard.
I intend to box this amp up nicely and use it for a few years.
Is there anything about veroboard layout with power amplifier circuits i should know or may cause me later headaches (i cant take another oscillating amplifier ill go mad..)?
Cheers Craig
P.S.
Also has anyone listened to these amps for full range speaker use before?.
I didnt get much choice in the circuit because all my transistors are NPN and its the only powerful Quasi circuit out there.
I have been working too much at uni to do much diyaudio but now summer is coming i am going to build an Ampslab C200.1
http://www.ampslab.com/c200qc.htm
I pretty much have all the bits necessary but i cant make PCB's. I am therefore going to have to use veroboard.
I intend to box this amp up nicely and use it for a few years.
Is there anything about veroboard layout with power amplifier circuits i should know or may cause me later headaches (i cant take another oscillating amplifier ill go mad..)?
Cheers Craig
P.S.
Also has anyone listened to these amps for full range speaker use before?.
I didnt get much choice in the circuit because all my transistors are NPN and its the only powerful Quasi circuit out there.
Keep the layout as compact as you can manage. Don't have the power connections for the output transistors going to the board, connect these straight to your power supply. Similarly, hard-wire the power resistors R18-R21 and don't put them on the PCB. Put C9 and R22 across your speaker output terminals. Similarly have D3/D4 (flyback diodes) on the heatsink hard wired.
Keep compensation capacitor C7 as close to the transistor as you can. Ideally, the next hole along. C3 should be soldered right over R7 as well.
Shorten the tracks with a drill bit to exactly the length they need to be. Don't allow the unused track to carry signals, or it will act as an antenna and inject noise into your circuit which can make it oscillate.
If you are careful, you can make it work on veroboard. I managed to make an Elliot P3A works on veroboard and these use CFP output arrangements which can be very sensitive to layout especially with fast output transistors.
Are you sure you can't make PCB's though? Do you have a laser printer you could use? If you do its possible to make good quality PCB's at home for cheap using the Laser Toner Transfer method as detailed here - http://www.fullnet.com/u/tomg/gooteepc.htm
Keep compensation capacitor C7 as close to the transistor as you can. Ideally, the next hole along. C3 should be soldered right over R7 as well.
Shorten the tracks with a drill bit to exactly the length they need to be. Don't allow the unused track to carry signals, or it will act as an antenna and inject noise into your circuit which can make it oscillate.
If you are careful, you can make it work on veroboard. I managed to make an Elliot P3A works on veroboard and these use CFP output arrangements which can be very sensitive to layout especially with fast output transistors.
Are you sure you can't make PCB's though? Do you have a laser printer you could use? If you do its possible to make good quality PCB's at home for cheap using the Laser Toner Transfer method as detailed here - http://www.fullnet.com/u/tomg/gooteepc.htm
Howdy AndrewT,
http://www.fullnet.com/u/tomg/gooteepc.htm
is very detailed except for one little bitty thing.
It doesn't work very well except for the smallest of boards.
Press-n-Peel Blue is still the best product.
http://www.fullnet.com/u/tomg/gooteepc.htm
is very detailed except for one little bitty thing.
It doesn't work very well except for the smallest of boards.
Press-n-Peel Blue is still the best product.
It works just great for me. It's all in the paper you use.
Cheapo inkjet gloss paper just seems to leave a plastic backer behind which is useless. I use Kodak picture paper which is a bit more expensive but still a hell of a lot less expensive than PnP Blue. It has worked very well, requiring only a little touch up with a pcb pen sometimes, and no soaking in water other than to cool the board. I've made a 200x100mm pcb with this method.
Cheapo inkjet gloss paper just seems to leave a plastic backer behind which is useless. I use Kodak picture paper which is a bit more expensive but still a hell of a lot less expensive than PnP Blue. It has worked very well, requiring only a little touch up with a pcb pen sometimes, and no soaking in water other than to cool the board. I've made a 200x100mm pcb with this method.
To each his own method.
PnP works every time for me, small or 200x266mm board, .0325" trace up to a big fill area. No water soak, no tooth brush scrubbing, no mess or touch up. Tried more than 20 different "papers" (Kodak too)and dozens of heating "methods" that all failed in comparison. At best, the etching managed to under cut the traces and always left the drill holes filled with fiber. Even distribution and pressure of the heating platen seems to be the most important part of these transfer systems. Altho toner quality also plays a part. I want a pro looking finished product, so a bit more $ is not the criteria.
My granpa said always buy the best, you'll never be disappointed.
PnP works every time for me, small or 200x266mm board, .0325" trace up to a big fill area. No water soak, no tooth brush scrubbing, no mess or touch up. Tried more than 20 different "papers" (Kodak too)and dozens of heating "methods" that all failed in comparison. At best, the etching managed to under cut the traces and always left the drill holes filled with fiber. Even distribution and pressure of the heating platen seems to be the most important part of these transfer systems. Altho toner quality also plays a part. I want a pro looking finished product, so a bit more $ is not the criteria.
My granpa said always buy the best, you'll never be disappointed.
Hi AndrewT,
The temperature of your iron, quality of the toner, pressure applied, and many other factors are in play.
A board that will fit well inside the iron area has the best chance to give you a "useable" result. That means a relatively small board in my experience.
Folks say that this method works well and they are happy with it. Try it for yourself. I find it time consuming, clumsy and messy. It produces a not very good board compared to a production house board which is my standard. PnP comes closest to that.
When I want a really good self made board, I go back to the "old" method of hand coating the copper clad, exposing with UV, developing and etch. Now that's really messy.
Practical issue, an 8" x 10" production house board "prototype"will set you back about $30 each in quantity of 10. Buy 200 and they are about $10. Make your own, maybe $2.50 using "expensive" PnP.
To each his own.
Regards
The temperature of your iron, quality of the toner, pressure applied, and many other factors are in play.
A board that will fit well inside the iron area has the best chance to give you a "useable" result. That means a relatively small board in my experience.
Folks say that this method works well and they are happy with it. Try it for yourself. I find it time consuming, clumsy and messy. It produces a not very good board compared to a production house board which is my standard. PnP comes closest to that.
When I want a really good self made board, I go back to the "old" method of hand coating the copper clad, exposing with UV, developing and etch. Now that's really messy.
Practical issue, an 8" x 10" production house board "prototype"will set you back about $30 each in quantity of 10. Buy 200 and they are about $10. Make your own, maybe $2.50 using "expensive" PnP.
To each his own.
Regards
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