BACKGROUND
The best consumer appliance timers only allow you to schedule down to the nearest minute. With most you are lucky to even get that accuracy. So why would you want to schedule something down to the nearest second? Well, for the general population this probably won't help you much; however, for the DIY community this is a must have and I'll show you why with a recent project of mine.I built an automatic dog feeder (if there is enough interest I may post the design later). The feeder puts the exact amount of food in my dog's bowl in the morning and night. For this design I didn't want to to use a 555 circuit or an Arduino... I just wanted to use a simple/cheap appliance timer to turn it on and off. Well, when I finished the dog feeder I found that it only took 5 seconds to dispense the food. If I let it go the whole minute then there would be a pound of food waiting to push my dogs into obesity. Hence, I needed an appliance timer that was capable of scheduling ON/OFF times down to the nearest second.
Meet the Chicago Electric Digital Timer (#95205). It sells at Harbor Freight for $10 or on Amazon for about the same. This timer is capable of being modded to enable second-resolution scheduling.
So let's do it...
1. Open it up. There are four philips screws on the back and another four on the back of the display section. On the circuit board the display plugs into you will see two pairs of solder pads below C7.
You can now see on the display the seconds. Now for programming
5. Plug in the timer and appliance and press the PROGRAM button.
6. Use the WEEK/HOUR/MIN buttons to set the start time. For seconds, use the ON/AUTO/OFF button.
You're done. I'm interested what other uses people are using this for. Post your ideas or questions in the comments section below.
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i had question about switching from 24 hr military time to 12 hr regular time with AM/PM? How do you do this with this timer. it doesnt say anything in the instructions but i know it can do it since i bought one that is showing AM/PM and the other one is 24 hr time. Also when i reset the small button i can see the LCD window clear and it has AM/PM on the display too. Any suggestions? It must be a combination of pressing couple of buttons to reset from 24 hr to 12 hr.
ReplyDeleteTo Unknown, 05.20.2020, I wondered this also, because after not using the device for six months, it displayed AM/PM, but strangely some of the times were 27:23, clearly not in the military time range, and it was not acting properly; if I hit upon the secret key combination, I will update it here. I hit the recessed reset button, and it reset to military, and after I reset the time, it worked properly displaying military time (I prefer). But thanks to Oh My Clegg for the hack because setting it up for seconds will be useful to me; thanks for taking the time to publish the hack you documented well.
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