Voltage regulator

[AgX]

Thank you.

 

[Hilo]

Over the years I have seen some older versions of the Focomat IIc come with a voltage stabilizer. If I am correct these were fixed to the rear of the baseboard.
Here what Leitz says about that in a Focomat IIc leaflet. The specific black version would be from the sixties and the beginning of the seventies. Perhaps it sheds some light on the discussion.

For color negatives or very dense negatives the Focomat can be equipped with a powerful 250-watt lamp. Since the burning life of this lamp at rated voltage is only three hours, it is advisable to use a dimmer switch with a variable resistor and voltmeter (see special leaflet No. 17-11). During adjustment of the desired picture size and framing the tamp is underrun. Full voltage, which is vari-able, is applied only during exposure. For color work, use of an automatic voltage stabilizer with dimmer switch and a regulation accuracy of ± 1 % is recommended. The use of one of these accessories will increase the life of the 250-watt lamp consider-ably. To enable these accessories to be employed in conjunction with the FOCOMAT II c , a special enlarging timer for the dimmer switch (Cat. No. 17 804) is required.

It is not often, but I do use a 250watt lamp now and then. I have three or four of those bulbs and don't remember any breaking.