Heater Power supplies - UK Vintage Radio Repair and Restoration Discussion Forum

apowell · 7th Jan 2011, 1:10 pm

Hi Gents,
I am in the middle of a portable radio project that requires a 7v heater voltage.I have built the battery eliminator and have realised that it is simply a resistor change to enable differerent heater voltages. This I intend to accomplish using some sort of switching. My question, is if I follow this route, what range of heater voltages should I cover?
Thanks for your time
Alec

Ed_Dinning · 7th Jan 2011, 1:23 pm

Hi Alec, from memory there appeared to be to be 3 main standards;
2Volts (lead acid accumulators, but also a few at 4v and 6v)
1.4V (most early dry battery portables)
7.5V (a lot of mains/ batt portables where the filaments are in series)

Are you using a regulator chip or a resistive dropper?
If the dropper, then you will need to vary the resistance for each different set due to the variation in curent draw.

Ed

ppppenguin · 7th Jan 2011, 1:27 pm

Also make sure that the voltage cannot rise unexpected during the switching operation. It wouldn't be funny if you were switching from 1.4V to 2V and the voltage spiked up to 7V while a set was connected.

7th Jan 2011, 1:10 pm	#1
apowell Retired Dormant Member Join Date: Oct 2010 Location: Watlington, Oxfordshire,UK Posts: 11	Heater Power supplies Hi Gents, I am in the middle of a portable radio project that requires a 7v heater voltage.I have built the battery eliminator and have realised that it is simply a resistor change to enable differerent heater voltages. This I intend to accomplish using some sort of switching. My question, is if I follow this route, what range of heater voltages should I cover? Thanks for your time Alec Last edited by apowell; 7th Jan 2011 at 1:12 pm. Reason: spelling error

7th Jan 2011, 1:23 pm	#2
Ed_Dinning Dekatron Join Date: Jan 2004 Location: Newcastle upon Tyne, Tyne & Wear, UK. Posts: 8,194	Re: Heater Power supplies Hi Alec, from memory there appeared to be to be 3 main standards; 2Volts (lead acid accumulators, but also a few at 4v and 6v) 1.4V (most early dry battery portables) 7.5V (a lot of mains/ batt portables where the filaments are in series) Are you using a regulator chip or a resistive dropper? If the dropper, then you will need to vary the resistance for each different set due to the variation in curent draw. Ed

7th Jan 2011, 1:27 pm	#3
ppppenguin Retired Dormant Member Join Date: Dec 2003 Location: North London, UK. Posts: 6,168	Re: Heater Power supplies Also make sure that the voltage cannot rise unexpected during the switching operation. It wouldn't be funny if you were switching from 1.4V to 2V and the voltage spiked up to 7V while a set was connected.