Timer-delay Off Switch prototype

Written by team member, Mark Ridley

Timer-delay Off Switch prototype

I’ve been working on and have now completed the prototype for the Timer-delay Off Switch.

It’s purpose is to conserve battery juice – especially handy as it gets later in the year and there’s not enough sunlight to fully charge the battery each day.

It’s being tested outside right now with my Solar Lithium Ion Battery Charger that’s powering two 5-LED strings.

I’m just waiting for another 1/2 hour-ish for it to switch the LED strings off.

Here’s a photo of an earlier incarnation while I was adjusting the timing. Either I can’t do sums or I’ve misunderstood how to work them out. Either way, check out my resistor Christmas tree!

resistor Christmas tree while adjusting the delay-to-off timings

It was made more difficult because I need to allow a switch to change the timing between a 5 hour interval and an 8 hour one.

I’ve got my prototype switched to 5 hours and the LED strings switched on at 18:35. It’s just coming up to 23:30, so I keep peering round the curtains to see if they’ve switched off yet.

23:31 Not yet…

23:35 Not yet…

While I’m waiting… reed switches are fragile! I used one in the housing I’m using, hot glued it on top of a steel washer so that the magnet to actuate it placed on the outside of the housing would have something to cling to.

A washer, as I found, is no good. The hole means you get poles on the inside of the hole and around the circumference. That means the reed switch wouldn’t work properly when the magnet was brought close.

(23:41 Not yet…)

So I tried to remove the hot glue and hardly touched the reed switch – alas, the glass casing of the reed switch broke. Boo hoo!

So when the replacement arrives, I’ll be using a small steel plate this time and not a washer.

23:45 Not yet… I guess this calls for a cup of tea 😉

As a side note, I notice that as the colours on the LED strings change, when it comes to blue, they’re very dim. From past experience I know this means that the battery voltage must be getting quite low – so the timer-delay off switch is really needed at this time of year when using a 1.5 Watt solar panel.

23:55 Not yet…

00:22 Yaay! They’ve switched off.

So that’s around 5 3/4 hours. How consistent is this? I’ll time it again tomorrow and update this post with the result.

Update: It’s now tomorrow and it took 5 1/2 hours to switch off this time.

See the now-completed project build tutorial for it here

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Mark Ridley is semi-retired and followed a career as a freelance business analyst. He has delivered business requirements resulting in many successful, high-profile projects for the private and public sectors, including the merging of the then Customs & Excise and Inland Revenue Inward Payment Systems into a single integrated system for the new HMRC. He now develops free-to-use online tools for artists and designers, helping them promote their designs on social media.

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