Heathkit Darkroom timer revealed glory!

[Tin Can]

I have a really nice 32 oz "persuader" for use with stuff which needs to be sacrificed to the gods.

I have a Heathkit PT-1500 Darkroom Timer. I can't remember when I bought and assembled it, but it is still a great timer. I keep it in the kitchen, use it for everything from cooking to developing film.

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This is PT-15, perhaps same but different age, maybe older as PT-1500 sounds so much better than PT-109, oh wait, wrong war.

[Corran]

I was tempted by that timer. I don't really like the one I have. But I was worried being home-built it might not be a good build. Guess I was wrong!!

When I was fairly young my grandfather, an air force electrical engineer, gave me a kit made for teens/young adults to build a few different projects - such as an alarm clock and such IIRC. My parents were mad at him because they didn't want me using a soldering iron but I was fascinated with electronics and his workshop so I actually built some of those things and learned a lot. Sadly I lost him soon after to a tragic car accident, otherwise I very likely would've gone down that route or similar rather than music.

Anyway...really cool that there's a tube in there! I didn't think it would need something like that but most of my experience with tubes is audio gear.

[Tin Can]

I was tempted by that timer. I don't really like the one I have. But I was worried being home-built it might not be a good build. Guess I was wrong!!

When I was fairly young my grandfather, an air force electrical engineer, gave me a kit made for teens/young adults to build a few different projects - such as an alarm clock and such IIRC. My parents were mad at him because they didn't want me using a soldering iron but I was fascinated with electronics and his workshop so I actually built some of those things and learned a lot. Sadly I lost him soon after to a tragic car accident, otherwise I very likely would've gone down that route or similar rather than music.

Anyway...really cool that there's a tube in there! I didn't think it would need something like that but most of my experience with tubes is audio gear.

I don't understand the circuit yet...The tube has only 2 pins in use. I guess it's purpose is diode for AC current rectification. So the heating element is not used, no wonder it only draws 5 watts. It has a thermistor for overheat condition, which would only occur if something burned. The case is very tight and fire would have a tough time finding much air or route outside the case. Seems safe enough to me. Controls 350 watts per markings.

[Jim Jones]

Tim apparently is right -- the VT appears to be a voltage regulator, not rectifier. There's at least one diode along the left edge of the interior in photo one. I built and used a Heathkit timer, perhaps this model, until it was destroyed in a darkroom fire. The bar knobs let one set the time in the dark without ever looking at the timer. The analog timer I designed and built lacked that convenience, but could be switched between Focus, Time, and Cancel with a single pole single throw floor switch. Two dual 741 timer ICs controlled everything. It and its schematics were also lost in the fire.

Electronic technology of the 1970s and earlier is still useful. I suppose the performance of solid state multi-band radio receivers far surpasses Hammarlund's magnificent SP-600, but that was obviously designed by men who made engineering an art. The three-tube radio I built in the 40s could pull in stations from around the globe, although it wasn't wired as neatly as the timer pictured earlier. In the 1920s, when radios were still luxury items, some were elegantly constructed and expensive. Soon the superhetrodyne design and pentode amplifiers of the '30s made high performance radios affordable to almost anyone. They lacked the character of the older radios.

[Ray Van Nes]

I have the PT-1500 which I assembled way back in the 80"s. Of course it did not work and had to have the Heathkit dealer fix it. It has worked faithfully ever since. It is programmable so I can have both the enlarger and processing all set up. I recently purchased a second one for my new darkroom for just on the wet side when I am doing film, so I do not have do the exorcist for the one on the dry side.

[Andy Eads]

The photos triggered many dusty memories for me. Kit electronics were my passion as a teen in the 60's. You scored a beauty.

[IanG]

I have a Heathkit Strobe a friend made in the early 70's. Note in the English language usage a Strobe is a stroboscope, this one can give variable rate pulses from a few per second to an interval of about 5-10 seconds, it can also be triggered with a hand switch (push button), I guess it would work off a camera flash socket as well.

Ian

[Ray Drueke]

Ah yes, electronic kits. I put together a Dynaco preamp and a power amp from kit form in the 60s while I was in the Navy. I wish I still had it - they're going for upwards of $300 on the 'Bay these days.

[Chauncey Walden]

I have two of those timers and unfortunately neither is accurate. I seem to recall something like 10-15% off.

[jon.oman]

In my youth, I built many tube based electronic kits. Sadly, although they all worked, I never kept any of them.