19-05-2024, 01:43 PM
(This post was last modified: 19-05-2024, 01:44 PM by Mike Watterson.)
HT Voltages
You can use about 120V for all HTs if you have the full datasheet. A 120/240 (or 110/220)V shaver outlet transformer is actually about 1:1 with a centre tap on the secondary for the US socket. It's got bathroom grade isolation and core power limiting (15 to 20W) and often a thermistor.
For smaller valves the screen volts can be a rectified power from centre tap to a wirewound pot to feed g2. The main anode supply can be via a halogen lamp and a shunt FET with gate driven from a 100K pot on a 9V PSU.
A 5V PSU with a fresh D cell in series makes a temporary 6.3V 300mA PSU for a heater.
Next I'll do some simple circuits. I'll test them first, so there will be a delay.
90V battery valves can actually be tested with 60V.
Power output devices are best tested in circuit.
You can use about 120V for all HTs if you have the full datasheet. A 120/240 (or 110/220)V shaver outlet transformer is actually about 1:1 with a centre tap on the secondary for the US socket. It's got bathroom grade isolation and core power limiting (15 to 20W) and often a thermistor.
For smaller valves the screen volts can be a rectified power from centre tap to a wirewound pot to feed g2. The main anode supply can be via a halogen lamp and a shunt FET with gate driven from a 100K pot on a 9V PSU.
A 5V PSU with a fresh D cell in series makes a temporary 6.3V 300mA PSU for a heater.
Next I'll do some simple circuits. I'll test them first, so there will be a delay.
90V battery valves can actually be tested with 60V.
Power output devices are best tested in circuit.
