I just set up my home darkroom. The only problem this far is that I do not have a darkroom timer. It is easy enough to use the print switch on the Omega Pro-Lab Time to turn on and off the light (the enlarger is plugged in to the clock). But, I would like to get a timer, so that the exposure time is a little more accurate and less of a bother. The cheapest one in town is:
Of course, I think I will hold out and try and get one on eBay. The only question I have is that will all timers (such as the one above) work with my enlarger. I have a Omega Chromega B Dichroic.
I usually use a clock that ticks loudly once a second. It is easy to divide the secend into quarters for finer accuracy. This method is more convenient than a timer where dodging and burning is needed.
Time O Lites work well for enlarging, and they're cheap on ebay, but they don't make noise. There are fancier timers which produce a beep every second which, as Jim says, is helpful during burning and dodging when it is difficult to watch what you're doing, and the timer at the same time. Some folks use a metronome, I'm more of a timer person, and I count off seconds in my head when necessary for burning or dodging.
Any electronic timer, and the mechanical Time-O-Lites will work with a Chromega B. You should already have a power supply and voltage regulater that comes with that enlarger. I have one - used it for decades with a Time-o-lite.
A little patience and something will come up on auction.
For a basic, starter timer look for a Gralab 450, 451, or 500. Should be able to pick one up for about $45. I don't like the Gralab 300 because you have to reset the timer each time so it is annoying for repetitive exposures. The old Time-O-Lite that I picked up was the same way and only goes up to 60 seconds. A Beseler digital timer should work well also.
For a step up, look at the Darkroom Automation timer advertised on this site for a lesser cost f-stop timer. My favorite is the RH Designs Stopclock Pro but that is some serious money for a timer.
The GraLab 400 is a 60 second timer w/auto reset - designed specifically for timing exposure - where a 300 is a 60 minute timer and would be best for timing development. They look almost identical. You really need (or should consider having) both.
I've only ever used Time-O-Lite's and I'm using an Omega D. I favor the mechanical, mostly due to being familiar w/ them. They are cheap secondhand and the 'professional' model will allow you to hook a footswitch up to it which is very handy for dodging and burning.
They are easy to repair and are built to withstand a lot of abuse. They are not as accurate as a digital timer, you can't expose for a fraction of a second reliably but i've never felt the need for this. Plus they have this charm that fits well with an older Omega.