Gralab 450 or 451 with Aristo Cold Light Head

[pdccamerqs]

Hi all,

In my darkroom I have a Beseler 23CIIXL equipped with an Aristo Cold Light Head. Currently I am using a vintage Time-O-Light timer. No problem with this setup, but I was just gifted both a Gralab 450 and a 451 enlarging timer. Has anyone used either of these with an Aristo head WITHOUT the 1200-A Aristo Contactor? Aristo says they recommend a timer that can handle an inductive (motor, transformer, etc.) load of at least 1200W https://www.light-sources.com/wp-content/uploads/2015/05/1200_contactor_info.pdf
The sticker on the back of the 450/1 timers indicates their maximum rated resistive load of 1200W, lamp load of 600W, or a motor load of 1/3HP, which is at least partially inductive.

Also, has anyone replaced a Aristo model 1200 contactor with a solid state relay, and if so, do you have any specific recommendation on make/model of relay?

Thanks,

Paul

 

[Kilgallb]

The aristo cold head is a big inductive load with lots of back emf (back electromotive force) that will generate high voltage for an instant at turn off, but that is enough to fry the Greylab digital timer.

Use a relay (mechanical) to relay line voltage to the aristo head. Energize the relay with 110 volts from the graylab.

For the same reasons stated, a solid state relay will also fry, so avoid them.

Here is a link to digikey for an appropriate relay. I use it on my Beseler head with an LED lamp. Don’t forget to order a socket.

https://www.digikey.ca/en/products/detail/te-connectivity-potter-brumfield-relays/KUP-14A35-120/45014?_gl=1*e7tnw3*_up*MQ..&gclid=EAIaIQobChMI05W1-eO2hgMViDWtBh0AoQs-EAAYASAAEgKwS_D_BwE

 

[Rick A]

I've been using a GraLab 505 with a Zone VI cold light head on my Beseler 45MXT for years without any issues.

 

[Alan9940]

Like Rick A, I've been using a Gralab 450 with an Aristo VCL4500 system on my Beseler 45MX for years without any issues.

 

[pdccamerqs]

The aristo cold head is a big inductive load with lots of back emf (back electromotive force) that will generate high voltage for an instant at turn off, but that is enough to fry the Greylab digital timer.

Use a relay (mechanical) to relay line voltage to the aristo head. Energize the relay with 110 volts from the graylab.

For the same reasons stated, a solid state relay will also fry, so avoid them.

Here is a link to digikey for an appropriate relay. I use it on my Beseler head with an LED lamp. Don’t forget to order a socket.

https://www.digikey.ca/en/products/detail/te-connectivity-potter-brumfield-relays/KUP-14A35-120/45014?_gl=1*e7tnw3*_up*MQ..&gclid=EAIaIQobChMI05W1-eO2hgMViDWtBh0AoQs-EAAYASAAEgKwS_D_BwE

Thanks so much - this is exactly the info I was looking for! Much obliged.

Paul

 

[pdccamerqs]

Like Rick A, I've been using a Gralab 450 with an Aristo VCL4500 system on my Beseler 45MX for years without any issues.

Thanks Rick and Alan! I appreciate the info!