| General > General Technical Chat |
| Replacements for old Valve Radio Power Supplies |
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| GlennSprigg:
OLD valve radios needed either mains power, or 'vibrator' circuits, or actual HV batteries. These days, (we) use battery eliminator units. I (we) can & do build circuits to re-create the needs for battery radios. Now I don't have a problem building many/various units, to replace the 'traditional' 'A', 'B', 'C' batteries to power such antique valve radios. The typical construction, is using variable out put voltages, to simulate the tube 'heater' volts, as well as the variable 'Plate' voltages, (and more!), usually attained by variable voltage regulators, and banks of 'Zenner' diodes for voltage division. The MAIN need/drawback/requirement is for the main Transformer!! One can 'scavenge' one from an old radio, with 'taps' for -45v, Com, +45v, and heater voltages etc.... Often, you need even higher voltages to inject into a circuit! However, whenever I find an old 'junk' receiver, I want to rebuild it, and not strip it for parts! hahaha... I just want an old 'tranny' to use for this 'use', as I can't build 'That' |
| schmitt trigger:
Hammond Manufacturing does sell "Classic tube" power transformers. Those will always have the essential windings, like CT-tapped plate voltage, 6.3V and/or 12.6V for the vast majority of heater voltages, and 5V for the rectifier tube, if you prefer those instead of solid state rectifiers. If you require another oddball voltage, you can always use another transformer, say 117/24V to provide that voltage. They even produce output transformers and chokes, in case you require them. All of the "big iron" transformers won't be cheap, but the prices are reasonable considering the sheer amount of steel and copper involved. Have a look: https://www.hammfg.com/electronics/transformers/classic Of course, there are other vintage transformer manufacturers, usually geared towards the "audio phool" community, with prices that will make you wet your pants. |
| pardo-bsso:
Is rewinding a transformer an option? I have several from cheap ups units that were beyond repair and they have most of the time (for my models) some low voltage secondaries and another one that can be cut and re-wired with a near 1:1 ratio |
| Shock:
There's also transformer rewinding and restoration if you have enough patience. You can either completely rebuild a transformer or rewind/repurpose an existing transformer or build a new one to spec. You can DIY simple winding tools out of a few bits of wood and a couple of bolts. For counting turns you can modify a cheap or old calculator, Dave did a video on this in Eevblog #962. You can get as elaborate as you like. Check youtube a few people show the general idea of whats involved in power transformer rewinding. |
| Cyberdragon:
ClassicTone also makes reproduction transformers. |
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