Darkroom Timer

A better question is why don't you make a blue. green, white LED array 10x10 light source? I would trade you several digital timers for that!

 

I see the advantage of a digital timer versus analog as being able to time to the 1/10 second when printing. For development, etc. the gray lab is just fine. I have no idea how to build one though.

 

@ Jerold: How about this one? http://www.heilandelectronic.de/html/deutsch/produkte/kaltlicht_main.htm

 

I used to build all sorts of stuff, but lately, I find my DIY enthusiasm fading. When an analog darkroom timer I had already resurrected once started acting up on me a couple of weeks back, I found a Beseler Digi-Timer 8187, new in box, at KEH -- "$59.98 was 259.95." I always thought most of those timers were way overpriced, but given that reduced price, it is now sitting in my darkroom and worked quite nicely for a print session last week. Seemed like my lucky week.

DaveT

 

I've settled on the Omega digital timer for a number of reasons. Unlike the Gralab 300, you don't have to keep resetting the timer, repeatability and accuracy is key. One less thing I need to do is helpful during a long printing session. The foot switch which has pedals for focus and time is the main feature that I like.

 

If you buy them in quantities to make one timer you will find the parts will run you well over $100. That's just for a pile of parts. For the time you will spend designing the electronics, laying out printed circuit boards/wire-wrapping, writing software and debugging you will be $500 ahead spending the time flipping burgers for minimum wage and buying a commercial timer.

If you are going to do it, do it because you would enjoy doing it. Don't do it just to save money - you won't.

 

Yes, but I would need to trade my Rolls Royce for an 8x10 version.

 

Priorities man..!

 

I bought a Gra Lab 520 digital timer at auction for $28.00. It is no longer in production so it and many others can be bought at very reasonable prices.
The display can be seen easily in dim light.

 

You will, you will...

People may debate about which f-stop timer to get, but owners of the timers all seem to agree that it was not money wasted.

The money spent will improve your work far more than if you spent the same amount on yet another lens.

 

Enlarging timers are plentiful and cheap on the used market. Not worth building one. You can get an old time-o-lite for $10. A Gralab 450 or higher number (or similar) for not much more if you're patient. Beseler, Kearsarge, etc.

 

I've used an Omega CT40 for over two decades. I love it. 0.1 sec time resolution, repeatable, simple keypad entry. I used the programable memories when I was processing E-6.

Yes, it's overkill, but the CT40 was designed to be everything to everyone.

 

Used timer like the Gralab 505, 520 etc.. are quite inexpensive. They are fine for most applications.
I also built my own timer but only when there is a need for functions that are not available with pre-built one.

 

If I use the ATMega chip, I would use only digital I/O and the LCD interface. I would not use ADC/DAC.

 

It turns out there are very few DIYers out there. I started by offering a kit of parts for a basic timer including a pre-programmed microprocessor - you would add your own transformer, case, and other condiments from the junque box and make a timer for, I can't remember the price, something like $15-20. Sold 2.

If you go to Radio Shack and buy everything new you are going to be missing a C-note by the time you walk out.

Have fun, though, it is one of life's more important rewards.

A basic AVR processor, suitable for a simple timer, can be had for less than a buck. It is probably the cheapest part of the timer.

AVR offered a development kit with a small graphics LCD, keyboard, processor and I/O drive for $50. I don't know if they still do. But add a relay and a wall wart and all you need to do is write the software. I think it plugged into a USB port for programming and debugging - saving the cost of a programmer and JTAG interface.

See the 'AVRFreaks' web site.

 

Cost is never the real issue in a DIY project like this. Regardless of the project the raw stuff can almost always be had cheaper or be dug out of the junk bin. Nothing wrong with that.

The urge to DIY comes from a real want to know how it works or for bragging rights to say "see what I did" or from being a cheapskate or from really being capable of the task at hand. I've qualified in all these camps at one time or another.

What I've learned over time is that my time is only worthy of stuff that I truly enjoy or that provides me a significant profit. If I'm going to give up free time, it better fit in one of those categories.

I built my own home because I had the skills, I could save myself lots of money, it was something I'd always wanted to do, and I had the time.

If you want to build a timer, build it. If all you want is to save a few bucks you are probably better off in the used market.

 

There are small development kits for Atmel and Microchip processors readily available. Atmel used to do one (perhaps still do) with an LCD display ('tho you will have to sort out some way of seeing that in the dark). C compilers are available FOC to download and gpl development sytems, code editors etc are also free. You can build a very powerful development environment for just the cost of the dev. board.

Back in the day there were at least three practical electronics magazines in the UK that had projects people could build - some simple (the ubiquitous 555 timer springs to mind ) - some using single-chip microcontrollers. They have all gone years ago. Show someone a small soldering iron now and they will try to use it as a stylus on their i-phone...

Oh, when not using the built-in timer of my AC1200 I use a metronome.

 

At one time I used a programmable controller as the timer and a PC as the operator interface.

 

Building, programming, and debugging your own can be difficult and may take a lot of time. But you can design it to work the way you want it to work. The Microchip controllers are dirt cheap. Some cheap assembled boards are also around. Basic Stamps and Rabbits are easy to work with. You can get red backlit LCD displays and red LED displays that interface. Many microcontrollers are available with built in timers that can simplify programming. Programming the interfaces for the keypad and the display can be tricky and difficult, but some careful shopping will probably get you parts that, while a bit more expensive, need minimal interface programming. Be sure you do a complete specification and design before you start buying stuff and putting it together, though.

 

When you do get a digi timer you will use it and all of it. You hear this statement from all walks of life "i do not know if i will use all the functions. Get one and enjoy.
They come up on Ebay.
Graham

 

Hello!. My first post to this forum for a very long time!

One of the nice things about analogue photography is that "DIY" can be part of the hobby if you want it to be!

My idea for an f-stop timer is to interface a Palm Pilot via its docking station to a PIC that simply responds to an ON/OFF command communicated via RS232. I have recently bought two Pilots for £1 each, so they are very cheap and the docking station provides RS232 and a nice "Start" button. The PIC would live in the same box as the power relay, allowing the Pilot to be remote, probably attached to the enlarger itself. There are a lot of public domain Palm development tools out there for free, so writing the application shouldn't present any problems. Question is, will I ever get round to it!