I've designed myself a shot timer. It's prototyped on breadboard now and the software is finished. Pretty simple. It just sleeps till you hit the button, then counts up to 59 seconds and goes back to sleep to save the batteries. LED displays look cooler than LCD, but they eat a LOT more power. Running off batteries means only turning on the displays when they're needed.
It's pretty large and sprawling on the breadboard. I'm going to solder together a nice compact one sometime next week for everyday use. It will have the blue displays. I like them better than green.
Got it all wired up and it works good, but I think I have a defective display. On one of the two displays the A and F segments are dim. I've triple checked the wiring and solder joints and all seems good. How annoying! Replacing that display will be a tough job.
It's 2-1/4 x 2-1/4 inch (57x57mm). I have Eagle and all the equipment to make photofab boards, though I haven't made any in a long time. With a PC board I could go smaller, though I guess there's not much point in going smaller than the battery pack.
This soldered prototype is just so I can test it for a while and see if I want to make changes. Running a breadboard for weeks around the espresso machine was sure to end badly, so a soldered version was a must for long term testing. I may experiment with smaller battery types and ultra-low power PICs, etc... A low power PIC on two AAA cells is no problem, but the 7-seg displays may be too power hungry (numeral 8 consumes 175ma). On the other hand, they only have to run in 60 second bursts. The sleeping 18F1320 PIC consumes something like 0.1 microamp - almost nothing.
EDIT: Hmm... Now I'm thinking of making a PC board and building an all-surface-mount one. I see Digikey has low profile SMT 7-seg displays too. SMT is so perfect for homemade PC boards. Much less drilling - you basically drill only for via's and the odd connector. Makes homemade double-side boards so much easier to do. I've done double-side boards with thru-hole components - takes a lot of planning and it's still VERY difficult. Without that thru-hole plating you have to solder both sides on many of the holes. Makes it tough...
"Joe", even to my less than masterful eye your gig is way cool. Suggestion: Why not use your given name? This site is a friendly place without a whole lot of spam, and what is there quickly gets disposed of. I'm a new Moderator, but I'm so impressed by the security around here, even after 7+ years. Just a thought. Cheers.
The OP has not logged on in over a year and a half, it is doubtful that he will ever reply, that is a problem with digging up very old threads (this thread is nearly 5 years old), very often the starter of the thread was here only for a short time to ask a question and they are gone.
There are many timers on the market, you need not make your own. All this one did is count seconds. That is a job that a clock on the wall can do for a lot less effort. I have a clock with a second hand in the kitchen, next to my coffee bar. All I do is wait until the second hand is on a number, which number does not matter, say it is the 4, then add 25 seconds to that and you get that the shot should end at the 9 mark, twenty seconds (4) and twenty five seconds are forty five seconds or the 9 number on the clock.
If that is too much math, there are lots of timers on the market on line for a few dollars. I am going to do a review of the Hario scale/timer unit soon, it both weighs the shot and has a built in timer to use too. It is designed for pour over service but it works just fine for espresso too but it is a bit pricy if all you are looking for is a timer.
In real life, my name is Wayne P. Anything I post is personal opinion and is only worth as much as anyone else's personal opinion. YMMV!
Feed the newbs, starve the trolls and above all enjoy what you drink!
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