DIY PSU build query...

[Desertboy]

Sorry, pedantic mode (it might be important for someone blindly following this to avoid damaging drivers etc.):

Wired two 45V windings in series and you get 72V DC off load?, there's something amiss there. Perhaps in parallel? - I'd expect a 45Vrms winding to present around 64Vpk-pk, probably 62V after rectification and smoothing. Add 10% for the 220VAC rated primary and the nominal 240VAC UK supply and you're getting within a gnats of the 72V.

Two 45V windings in series you should expect 90VACrms, leading to around 128Vpk-pk, around 126V after rectification and smoothing. And then you can play games with the 220VAC primary versus nominal UK supply.

For reference, I also bought a toroidal tx from Maplin on closure...



That pokes out 72V off-load, rectified and smoothed, measured with cheap Chinese current/voltage DMM panel meters. Two secondaries driving two separate circuits - but this should give the same voltage as two secondaries in parallel (not series). The maths for mine = 50VAC * SQRT(2) - 2 * Vf(rect) = 69V - within about 5% of measured - I'm happy with that.

The bridge rectifier drops the voltage, it converts AC to DC you connect both outputs in series run it through the rectifier and 72v out the other side in DC.

You need capacitors to clean up the DC.

In center tapped full wave rectifier, only one diode conducts during each half cycle. So the voltage drop in the circuit is 0.7 volts. But in the bridge rectifier, two diodes which are connected in series conduct during each half cycle. So the voltage drop occurs due to two diodes which is equal to 1.4 volts (0.7 + 0.7 = 1.4 volts). However, the power loss due to this voltage drop is very small.

https://www.physics-and-radio-electr...rectifier.html