Author Topic: Well that didn’t work.  (Read 4277 times)

Furrari

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Well that didn’t work.
« on: February 03, 2018, 10:47:21 PM »
In a recent post on another thread I said that all you needed for a boot light switch was a miniature PIR and a 3v relay.  JJ asked for details.  As I had the bits I said I would build him one.

I normally draw a circuit and breadboard the circuit when I start a job but as there was only two components I didn’t bother, I just soldered it on a bit of vero board.  Tested it and it didn’t work.  Hme.....

I put 3v across the relay coil and it clicked in OK.  5v across the PIR and the correct 3.5 volt output, so why wouldn’t it work.  On to google, the specs of the component said it should work.  Then I realised the bits were built of Chinesium.  When I checked the output voltage of the PIR with the relay coil in circuit the output of the PIR dropped to near zero.  It seems that not all components give the rated output.

Solution.  Design a better circuit.  I’ve drawn the circuit but as it’s in pencil it won’t photograph, so tomorrow I’ll draw it a bit better, photograph it and post it.
Not all problems can be solved with gaffer tape.  For those there is WD40.
Not even gaffer tape can fix stupid, but it can mask the sound.

If you can’t buy it or steal it you have to make it.

Furrari

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Re: Well that didn’t work.
« Reply #1 on: February 04, 2018, 11:53:58 AM »
This time I drew a circuit.  This is the circuit I drewed.

I was going to show a picture of the circuit breadboarded but I think I took it apart before I tried to take a picture.
« Last Edit: February 04, 2018, 12:27:52 PM by Furrari »
Not all problems can be solved with gaffer tape.  For those there is WD40.
Not even gaffer tape can fix stupid, but it can mask the sound.

If you can’t buy it or steal it you have to make it.

Furrari

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Re: Well that didn’t work.
« Reply #2 on: February 04, 2018, 01:58:11 PM »
And here it is built up.  Next is a box to put it in.
« Last Edit: February 04, 2018, 02:04:05 PM by Furrari »
Not all problems can be solved with gaffer tape.  For those there is WD40.
Not even gaffer tape can fix stupid, but it can mask the sound.

If you can’t buy it or steal it you have to make it.

johnjames

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Re: Well that didn’t work.
« Reply #3 on: February 04, 2018, 04:17:26 PM »
Hi Mick looking forward to seeing it in the flesh keep up the good work John James.   8)8)
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Furrari

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Re: Well that didn’t work.
« Reply #4 on: February 04, 2018, 05:48:39 PM »
Oops.  As one of our eagle eyed viewers has pointed out, in the circuit drawing, the EMF suppression diode across the coil of the relay is drawn backwards.  I’ve wired it the right way round, I know that 'cos it works.  If the diode is the wrong way round it would release the magic smoke out of the transistor.
Not all problems can be solved with gaffer tape.  For those there is WD40.
Not even gaffer tape can fix stupid, but it can mask the sound.

If you can’t buy it or steal it you have to make it.

Furrari

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Re: Well that didn’t work.
« Reply #5 on: February 04, 2018, 06:16:17 PM »
I’ve designed and printed the box but I won’t post until it’s all finished with the electronics installed.

One area I Way have a problem with are the threads.  You can’t tap an M3 thread into a PLA box, it’s just too small.  To put the thread in you use a brass insert.  I have a temperature controlled iron but the pillar drill I need won’t be with me until the end of the week and will need modifying anyway.  So I’ll have to just use the iron and a long screw to line them up, and hope I can get them upright enough by eye
Not all problems can be solved with gaffer tape.  For those there is WD40.
Not even gaffer tape can fix stupid, but it can mask the sound.

If you can’t buy it or steal it you have to make it.

johnjames

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Re: Well that didn’t work.
« Reply #6 on: February 04, 2018, 08:01:27 PM »
You can do it I've got faith in you just have a few whiskies before you start keep up the good work John James.  ;D;D
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Furrari

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Re: Well that didn’t work.
« Reply #7 on: February 05, 2018, 07:19:50 PM »
The box is designed and printed.
Just a picture of the box ready for printing.  The whole gubbins is now assembled and is on test.  It turns on every time you walk in the room.  It stays on for as long as you flap your arms I front of it and the turns off about 10 seconds after you stop.  This time is adjustable.
Not all problems can be solved with gaffer tape.  For those there is WD40.
Not even gaffer tape can fix stupid, but it can mask the sound.

If you can’t buy it or steal it you have to make it.

Jez

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Re: Well that didn’t work.
« Reply #8 on: February 05, 2018, 09:17:38 PM »
If you were to produce these to sell on, what would you charge? I could be interested in one too.

Jez
Jez

Furrari

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Re: Well that didn’t work.
« Reply #9 on: February 05, 2018, 11:35:55 PM »
Jez.  No idea.  I made it out of bits I had lying round ( as you do).

I already have a diffent version of the PIR in the load cover of the Furrari.  I’m going to play with that before I build one for anybody else.

The first version (for JJ) is probably senseative as the cat keeps setting off by walking past it.  15 feet away.
Not all problems can be solved with gaffer tape.  For those there is WD40.
Not even gaffer tape can fix stupid, but it can mask the sound.

If you can’t buy it or steal it you have to make it.

Furrari

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Re: Well that didn’t work.
« Reply #10 on: February 05, 2018, 11:47:27 PM »
Jez.  I’m working on the Mk 2 version at the moment using a smaller lense version.  I already have the sensor araldited into the Furrari load cover.
Not all problems can be solved with gaffer tape.  For those there is WD40.
Not even gaffer tape can fix stupid, but it can mask the sound.

If you can’t buy it or steal it you have to make it.

Furrari

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Re: Well that didn’t work.
« Reply #11 on: February 06, 2018, 12:18:43 PM »
Here it is.  As promised, a picture of it all in a box.  All it need is a fuse and the lid screwing on..

The two orange thingies are potentiometers that control the sensitivity ( range it detects at) and the other the minimum length of time it stays on for.  The LED monitors the fuse. ( lights up if the fuse is blown)
« Last Edit: February 06, 2018, 12:24:56 PM by Furrari »
Not all problems can be solved with gaffer tape.  For those there is WD40.
Not even gaffer tape can fix stupid, but it can mask the sound.

If you can’t buy it or steal it you have to make it.

Jez

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Re: Well that didn’t work.
« Reply #12 on: February 07, 2018, 05:36:14 AM »
Neat. Well done. There are some very clever people and you are obviously one of them!

Way beyond my understanding......

Jez
Jez

Furrari

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Re: Well that didn’t work.
« Reply #13 on: February 07, 2018, 08:35:42 AM »
Jez.  Thank you.  I feel very fortunate that I am just as happy with an angle grinder as a box of transistors, although I have a lot to learn about them.  I didn’t have time for playing with them when I was at work.  Now I’m retired I’ve started learning lots of new and interesting things.
Not all problems can be solved with gaffer tape.  For those there is WD40.
Not even gaffer tape can fix stupid, but it can mask the sound.

If you can’t buy it or steal it you have to make it.

johnjames

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Re: Well that didn’t work.
« Reply #14 on: February 07, 2018, 01:22:06 PM »
Hi Jez you think that's good you wait till you see he's yellow west coast at Stoneleigh and see what he's done to the interior it doesn't look like a Mercedes at all and also your meet gorgeous George as well keep up the good work with the 250 John James
Drive it like you stole it