I do have one of the Protection PCBs left over. I can include that with an order if someone is interested.. I will probably order the CFA boards tomorrow and it usually takes about three weeks from the time of ordering so I should receive them around January 7th for those interested.
Blessings, Terry
Blessings, Terry
The protection board is sold. I ended up ordering 7 pair of the CFA boards so just PM me if interested. Can't wait to build this one.
I think, sheet metal strip is ok, I would make it roughly 3cm tall. It doesn't noticeably heat-up, however it ensures thermal feedback, so thermal contact with Vbe multiplier is important.
In overall, at 35mA per pair, the whole amp runs rather cool - nothing gets really hot.
Is thermal run-away not an issue with this amp?
Also, did you happen to do a BOM for this amp? I ask because the schematic doesn't show which resistors need to be more than 1/4w.
Also, did you happen to do a BOM for this amp? I ask because the schematic doesn't show which resistors need to be more than 1/4w.
It's not lateral fets so it could be a problem if the main heat sinks aren't large enough. This is the amp he couldn't get the driver's to warm up on. That's why I was asking about driver heat sink.
You know me, always trying to learn. In my mind, if the drivers are not producing much heat, perhaps it would be better to fly the VBE on wires and mount on top of one of the outputs for better thermal tracking.
I'm in the same boat. I think this one needs to track the temperature of the drivers themself. This is an odd driver design. There's one for each output device.
Hi guys,
CFP is a very special arrangement. A quote from an open web page by Douglas Self (http://www.douglas-self.com/ampins/dipa/dipa.htm):
"The CFP topology is generally considered to show better thermal stability than the EF, because the Vbe of the output devices is inside the local NFB loop, and only the driver Vbe affects the quiescent conditions."
In this case, we have to track the drivers' temperature. No problem with thermal runaway at all. The amp runs MUCH cooler, than normal EF or Source Follower (in case of FETs).
Cheers,
Valery
P.S. Besides that - it sounds great! 😉
CFP is a very special arrangement. A quote from an open web page by Douglas Self (http://www.douglas-self.com/ampins/dipa/dipa.htm):
"The CFP topology is generally considered to show better thermal stability than the EF, because the Vbe of the output devices is inside the local NFB loop, and only the driver Vbe affects the quiescent conditions."
In this case, we have to track the drivers' temperature. No problem with thermal runaway at all. The amp runs MUCH cooler, than normal EF or Source Follower (in case of FETs).
Cheers,
Valery
P.S. Besides that - it sounds great! 😉
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Yes, those are actually filtering 15V supply for the Op-Amp (DC servo). So, if they fit the PCB - no problem...
BTW, numbers for the caps in mm show the pins interval.
BTW, numbers for the caps in mm show the pins interval.
I've got to get one amp running before Terry. He should have his boards any day now. He'll probably have them running a couple hours later.
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