17-03-2025, 04:50 PM
(This post was last modified: 17-03-2025, 04:54 PM by Mike Watterson.)
The Convettes, IMO, are display only. The voltage will rise too much on LT if the O/P valve is unplugged or goes O/C. They are rubbish.
I've used a shaver transformer with full wave via 2 x 1N4007, two caps, series resistor and bleed resistor to limit HT when no LT. If you want closer to ideal 80 to 85V then add a shunt regulator.
A DC PSU with series resistor and 2 x 1N5407 as a series pair as shunt regulator for the 1.35V. Use an LM315 at 6.8V for a 7.5V battery set.
The NiMH are a bit higher than the NiCd. The filaments are ideally run at 1.4V max, and 1.35V was recommended for a PSU. Using 1.3V is fine. The end point of the Zinc cell was 0.9V to 1V, but the DK9x would typically stop at 1.1V. So NiCd are marginal and NiMH are fine.
Similarly a 90V HT pack is nearly 100V no load and new, but end point of about 56V! So 75V to 85V HT is fine.
I've used a shaver transformer with full wave via 2 x 1N4007, two caps, series resistor and bleed resistor to limit HT when no LT. If you want closer to ideal 80 to 85V then add a shunt regulator.
A DC PSU with series resistor and 2 x 1N5407 as a series pair as shunt regulator for the 1.35V. Use an LM315 at 6.8V for a 7.5V battery set.
The NiMH are a bit higher than the NiCd. The filaments are ideally run at 1.4V max, and 1.35V was recommended for a PSU. Using 1.3V is fine. The end point of the Zinc cell was 0.9V to 1V, but the DK9x would typically stop at 1.1V. So NiCd are marginal and NiMH are fine.
Similarly a 90V HT pack is nearly 100V no load and new, but end point of about 56V! So 75V to 85V HT is fine.
