@Mark Johnson
with 2x22Vac, we got around 2x30Vdc after rectifier... can I use a 2x24Vac transformer and a CRC instead of C5 and C6 to get the same right voltage (around 2x30Vdc) before FB1 and FB2 ?Thanks
Damien
With the heatsinks specified on the UDP3 detailed parts list, the power transistors will survive nicely if you use a 2 x 24VAC transformer.
Unfortunately, the first stage electrolytic capacitors will not. Especially when the AC mains voltage is at the top end of its (Nominal ± Tolerance%) range. These electrolytic capacitors need to be rated for 50 volts when using 24VAC secondaries.
The detailed parts list tells you the required lead spacing (to fit the PCB footprint on UDP3) and the capacitor diameter; these will help you perform a Parametric Search on distributor websites like mouser.com . Capacitor height is 100% your choice; pick any range you can live with. I personally prefer electrolytic capacitors which are not as tall as the heatsinks (26 mm) but sometimes that's not possible with the parts in stock and on the shelf, the day I am placing an order.
Unfortunately, the first stage electrolytic capacitors will not. Especially when the AC mains voltage is at the top end of its (Nominal ± Tolerance%) range. These electrolytic capacitors need to be rated for 50 volts when using 24VAC secondaries.
The detailed parts list tells you the required lead spacing (to fit the PCB footprint on UDP3) and the capacitor diameter; these will help you perform a Parametric Search on distributor websites like mouser.com . Capacitor height is 100% your choice; pick any range you can live with. I personally prefer electrolytic capacitors which are not as tall as the heatsinks (26 mm) but sometimes that's not possible with the parts in stock and on the shelf, the day I am placing an order.
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