Exposure Timer

Hi,

I've only recently set up my new darkroom from bits and peices given to me secondhand. I don't have a timer on my old Zenith enlarger, which means I have to reach round the back to switch it on/off and count the seconds down on the clock - which is quite clumbersome, perticulary if I'm trying to shade areas of the image at the same time.

Since money is a bit tight I'm considering building my own exposure timer to controll my enlarger. I wondered if anyone else has any experance of this and could point me to some circuits.

The best one I've found so far is:

http://www.chipcenter.com/circuitcellar/september01/c0901nr1.htm

Thanks in advance,

Ben.

There is a guy in one of the newsgroups that is selling an electronic kit for a timer. I will find it and send you the info. There are certain things you will need beyond the kit/

lee\c

here is the message I was talking about for the electronic timer.

<<<I am offering a DIY timer kit for $28 plus actual shipping
<<<as a non-profit enterprise.

<<<The timer is a two digit unit with a range of 0.1 second to
<<<990. seconds.

<<<The kit contains all the key electronic items:
<<<Pre-programmed microprocessor
<<< Displays
<<<Relay
<<< Keyswitches and keycaps
<<< Capacitors
<<<Resistors
<<<Diodes
<<< Transistors
<<< Ceramic crystal

<<<Documentation consists of operating instructions, construction
<<<tips and schematic.

<<<You will have to supply a wiring board. A single-sided PCB
<<<artwork is included. Wire-wrap can also be used for the project.
<<<Not included are parts most hobbyists have in their junque
<<<boxes: line cord, 6.3 v transformer, wire ....
<<<You will have to make your own enclosure.

<<<Enclosures, transformers and such are all available at
<<<Radio Shack & Co. at reasonable prices. Resistors and such
<<<are also available at Radio Shack, but they charge $.50 each
<<<for them when they cost $.01 each in bulk -- and so I am
<<<including all the (what should be/are) low-cost items in
<<<the kit.

<<<Please email back if you are interested or wish a copy of the
<<<timer description.

<<<--
<<<Nicholas O. Lindan, Cleveland, Ohio nolindan@ix.netcom.com
<<<Consulting Engineer: Electronics; Informatics; Photonics.>>>

lee\c

Great!

Thanks, that sounds like just the kind of thing I had in mind. A pre-programmed microprocessor would save me considerable hassle too.

Thanks,

Ben.

If you have a Palm Pilot or compatible, there's a freeware for it - Foto Timer that do a lot of things.

http://www.jan-exner.de/software/fototimer.html

Besides, I've designed (and I'm on the way to build a prototype) a quite simple interface to control an enlarger/safelight using it.

If you're interested, pls let me know.

Jorge O

I can't believe that you can't find something used cheaper than buying all the individual components to build one. Check Ebay, local want ads, local photo club. Maybe an APUGer has an older one that they have upgraded from and no longer use. I don't know, but those Radio Shack components add up awfully fast. Best of luck whichever way you go.

Neal

check ebay, they have timers as cheap as 5 bucks:

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