neon flasher problem

If you use relays you need snubbers accross the contacts and a suitable vdr. You need much the same accross your triac, triacs dont allways turn off verywell with inductive loads antiparallel scrs might be needed, to reduce inrush you need to fire the triac at 90deg not 0deg and keep it on with either dc or a stream of pulses.

Rasi,

you may have an interesting problem regarding the transformers

when you suddenly turn off an iron core transformer, it retain the flux level it was at at turn off in the core. The next time you turn it on ,the flux level continues from where it left off....

If by chance, the xformer is turned off at the peak of the AC wave, it will retain a large flux level. If by chance it is turned on at the zero crossing , the flux level will try t oincrease from the high starting point and can possible go into saturation. If this happens, the inductance goes way down and thew current way up. This lasts for a cycle or two and is very damaging to the contacts.

Solutions? Some kind of soft turn off and soft turn on.. maybe a low wattage incandescent bulb wired ACROSS each relay contact ( the incandescent light will be on when the neon is off.) This will allow the core to turn off softly and become demagnizied and will allow some low level of current to flow. Also maybe a slow start PTC device in series with each transformer to limit the inrush turn on current.

good luck

Mark

On 28/11/2005 the venerable snipped-for-privacy@gmail.com etched in runes:

Try SCR based solid state relays with zero-crossing detection, such as Crydom EZ240D12S (one for each transformer would be best). Should be OK without snubbers but for all the cost you might want to put a Semikron SKRC440 across each relay.

HTH Wolfgang

You could try one MOC3083/BTA16 triac/snubber at each transformer. You don't have one inductance created peak to charge the cap, you have one from each transformer.

Ed