Just a note - the amp was built exactly like in the schematic, with an exception of the Schottky diodes.
Instead of MBR735, I used SBR10U45
https://www.digikey.com/en/products/detail/diodes-incorporated/SBR10U45SD1-T/4250086
MBR735 was used in the sim, because its model is built in LTSpice.
Instead of MBR735, I used SBR10U45
https://www.digikey.com/en/products/detail/diodes-incorporated/SBR10U45SD1-T/4250086
MBR735 was used in the sim, because its model is built in LTSpice.
It's a leftover from lt spice open loop gain simulation. Ignore it, and treat it as a continuous wire connection.
Probably “better” result than 2N3055’s - right up till they blow out. TIP35’s only real weakness is poor SOA. Not only is the breakpoint low (30V), but falls faster than anything I’ve ever seen except for the MJ1103x series darlingtons. And they mean it too - they’re not just sandbagging. At lower voltage the will drive all kinds of current and still not run out of gain but that voltage limitation is a b****.
TIP35C have 100V CE voltage, you sure they will blow at 30V rails?
I've never used them, but I'm planning to. Bought them cheap....
There is no SOA plot in any TIP35 data sheets I checked..
I've never used them, but I'm planning to. Bought them cheap....
There is no SOA plot in any TIP35 data sheets I checked..
They used to. Even the ST data sheet. Looks like it’s gone now. The breakpoint is at 30V and it falls like a stone. Even the old 2N6488 holds up better at 40V. TIP142 is more rugged. But unfortunately, darlington which isn’t ideal in this design. On 30V rails they are fine, and the amp will drive 2 ohms without running out of gain or frying drivers. 40V supplies and 4 ohms is instant death, lot of horror stories about people using them for guitar amps and giving up on them.
TIP35 does have nice flat hFE curves out to 10A without that annoying fall off at low current. I have the 35/36 in an amp with a single 48V supply (and output capacitor). And in a lot of store bought car amps.
TIP35 does have nice flat hFE curves out to 10A without that annoying fall off at low current. I have the 35/36 in an amp with a single 48V supply (and output capacitor). And in a lot of store bought car amps.
And the 10 ms curve doesn’t give you ANY meaningful headroom. Most types are way better about that.
Just finished another op-amp Circlophone build (for my sister), this time with active cooling.
Same schematic and PCB, but output devices are plastic.
Works great, and running cooler.
Also tried different, 2-layer aluminum chassis that is less time consuming to machine.
Same schematic and PCB, but output devices are plastic.
Works great, and running cooler.
Also tried different, 2-layer aluminum chassis that is less time consuming to machine.