11-06-2016, 07:43 PM
Old thread, but Google found it while I was searching for this one: http://www.vintage-radio.net/forum/showt...hp?t=49109
With the addition of 1 diode - neatly under the PCB - you can give these protection against "load dump". And while it's apart, add one in parallel with the output to protect against other external nasties. The scan of the diagram found in post #5 includes these (added in pencil).
A friend of mine discovered the "load dump" problem in a fairly dramatic way. He was using one to charge a small-ish lead-acid battery - fortunately this was outside in the garden. The power was interrupted, so the battery did the usual damage to these (VT5 IIRC). When the power was restored, pretty much all of the unregulated voltage was available to the poor battery. After a suitable delay, the battery exploded
With the addition of 1 diode - neatly under the PCB - you can give these protection against "load dump". And while it's apart, add one in parallel with the output to protect against other external nasties. The scan of the diagram found in post #5 includes these (added in pencil).
A friend of mine discovered the "load dump" problem in a fairly dramatic way. He was using one to charge a small-ish lead-acid battery - fortunately this was outside in the garden. The power was interrupted, so the battery did the usual damage to these (VT5 IIRC). When the power was restored, pretty much all of the unregulated voltage was available to the poor battery. After a suitable delay, the battery exploded
