Timer for exposure unit

hiroh · Apr 12, 2023

I made my standard exposure unit and I have a power switch built-in. I use my phone as a timer and I manually switch on and off the exposure unit. It would be nice to have a small device that can be programmed to turn the power off after certain period, but all I can find on Amazon works in hours only, and I need seconds, because my exposure is 3:30 min. Has anyone found something like this?

albada · Apr 12, 2023

You need a darkroom enlarger timer. Here are some: B&H enlarger darkroom timers

hiroh · Apr 12, 2023

Great, this GraLab looks cool, but it's an expensive for what it does, but I guess I'll give it a try. Thanks!

Rick A · Apr 12, 2023

You can buy used GraLab 300 timers for cheap on EBay. I use one to control my UV exposure unit, they can be set in seconds and minutes up to an hour.

hiroh · Apr 12, 2023

Yeah, they are really cheap on eBay.

How easy is it to set the precise time? Is it clicky, so i can count three clicks for three minutes, or do I have to fiddle with it to get it correct.

For me, the phone is the easiest, because I just press the side button and say "timer 3 1/2 minutes" to Siri and it starts counting down. But then, I really have to pay attention when the time is up to turn off the power, so for that reason I want something automatic, but has to be quite easy to set, like blindfolded

glbeas · Apr 12, 2023

Yes the minute hand clicks and the second hand you just push to the correct time and flip the switch to turn it on.

koraks · Apr 12, 2023

Something like this seems appropriate: https://www.banggood.com/AC110V-220...er-Control-Switch-Relay-Module-p-1747479.html
There's a plethora of similar/identical modules being sold on sites like ebay, banggood and aliexpress. The one above is just one of the first ones that popped up on a 'timer module' search. Give it a try.

Btw, I've used a bare-bones version of that module for years in my UV tube exposure unit. Worked fine.

PS: I recently repaired a couple of Hauck darkroom timers, which are conceptually similar to the Gralab timers. Just my humble opinion, but I find that sort of equipment antiquated, error prone, bulky and ridiculously expensive for what it is. These devices made perfect sense in the 1970s, but today...not so much. If you enjoy your Gralab, Hauck etc., feel free to do so. Not trying to talk you out of it. I just choose differently, to each their own and all that.

Rick A · Apr 12, 2023

There's been GraLab 300 timers in my darkroom since the 1960's. At one time, I decided to sell them all off and replaced them with digital timers, I missed the simplicity of them and bought another. It's like keeping company with an old friend. I kept the digi's for my enlargers, but the 300 operates my UV unit, 95% of my work is done using alt processes these days.

koraks · Apr 12, 2023

Rick A said:
It's like keeping company with an old friend

That I understand

jeffreyg · Apr 12, 2023

My GraLab has been in use for 52 years. It has a buzzer if you doze off during a long exposure 🥹. I don’t use it for my enlarger but for developing film and pt/pd printing. However I don’t shut down the light box during a session For the enlarger I use a digital enlarger timer. Just used the GL when developing film a few minutes ago Stayed awake for the 8 minutes so the buzzer wasn’t necessary

Sirius Glass · Apr 12, 2023

I have a digital time that allows me to do minutes and seconds or seconds and tenths of seconds. Check for one that is compatible with your enlarger.

payral · Apr 12, 2023

I connect these timer (cf pdf included) to my UV unit. It works like a charm

Timer for exposure unit

hiroh

albada

hiroh

Rick A

hiroh

glbeas

koraks

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Rick A

koraks

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jeffreyg

Sirius Glass

payral

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Timer for exposure unit

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