Power supply voltage doublers - Page 2 - UK Vintage Radio Repair and Restoration Discussion Forum

PJL · 22nd Sep 2018, 1:05 pm

Less than convinced that this is cost saving on the HG88 as it was not standard practice. It ends up using 3 separate capacitors and a resistor (including the RC smoothing) compared to a dual-electrolytic and a resistor for the traditional design. There is financial benefit in getting rid of the centre tap but a bridge rectifier is typically used for that.

Herald1360 · 22nd Sep 2018, 2:30 pm

But a bridge is a pain needing two extra isolated diodes- more expense in a valve realisation.

PJL · 22nd Sep 2018, 3:05 pm

Quote:

Originally Posted by Herald1360

But a bridge is a pain needing two extra isolated diodes- more expense in a valve realisation.

The HG88 uses SS rectifiers.

PaulR · 22nd Sep 2018, 3:37 pm

Having just done a bit of research on the Fisher 400 and seen the price asked for them I had better dig it out of the loft and get those capacitors changed!

turretslug · 24th Sep 2018, 8:37 pm

Quote:

Originally Posted by Herald1360

But a bridge is a pain needing two extra isolated diodes- more expense in a valve realisation.

I daresay a determined/obsessive/contrary person could make a single heater winding thermionic bridge using high-cathode-insulation TV efficiency diodes....

Herald1360 · 24th Sep 2018, 9:32 pm

But not a commercially driven enterprise with bean counters breathing down the designers' necks.

22nd Sep 2018, 1:05 pm	#21
PJL Dekatron Join Date: Sep 2005 Location: Seaford, East Sussex, UK. Posts: 5,997	Re: Power supply voltage doublers Less than convinced that this is cost saving on the HG88 as it was not standard practice. It ends up using 3 separate capacitors and a resistor (including the RC smoothing) compared to a dual-electrolytic and a resistor for the traditional design. There is financial benefit in getting rid of the centre tap but a bridge rectifier is typically used for that.

22nd Sep 2018, 2:30 pm	#22
Herald1360 Dekatron Join Date: Feb 2007 Location: Leominster, Herefordshire, UK. Posts: 16,535	Re: Power supply voltage doublers But a bridge is a pain needing two extra isolated diodes- more expense in a valve realisation. __________________ ....__________ ....\|____\|\|__\|__\_____ .=.\| _---\__\|__\|_---_\|. .........O..Chris....O

22nd Sep 2018, 3:37 pm	#24
PaulR Dekatron Join Date: Oct 2003 Location: Southport Lancashire, UK. Posts: 3,233	Re: Power supply voltage doublers Having just done a bit of research on the Fisher 400 and seen the price asked for them I had better dig it out of the loft and get those capacitors changed! __________________ Paul

24th Sep 2018, 9:32 pm	#26
Herald1360 Dekatron Join Date: Feb 2007 Location: Leominster, Herefordshire, UK. Posts: 16,535	Re: Power supply voltage doublers But not a commercially driven enterprise with bean counters breathing down the designers' necks. __________________ ....__________ ....\|____\|\|__\|__\_____ .=.\| _---\__\|__\|_---_\|. .........O..Chris....O