balidey
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| posted on 27/3/08 at 09:43 AM |
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12v timer circuit needed (I think)
I am soon to be getting a people carrier (I know this is a kit car forum, but you seem to be a great source of all info). The car will be used mainly
for my wife and she hates big cars, so I am thinking about getting a reverse sensor kit.
The way they operate is to switch the rear sensors on when reverse light has power. Seems sensible enough, but some kits have front sensors too. I
asked a seller on e-bay how the front ones came on, his reponse was they are switched on by the brake light feed.
Now that seems odd to me, so everytime you brake the front sensors come on.
What I was thinking of doing was fitting fronts and rears, but having them connected to a dash mounted switch, so when you want to use the sensors,
just turn them on, when not needed, turn them off.
But then I thought it must be possible to just have a push button to turn them on and have a delay timer (say 2 minutes) to then automatically turn
them off.
Sensible idea? or not?
So, anyone point me in the direction of a suitable circuit diagram?
Or has anyone got experience of these sensor kits and can offer any other advice......
Apart from, learn to reverse properly 
Thanks in advance for your help,
Steve
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Paul TigerB6
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| posted on 27/3/08 at 09:48 AM |
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I would have thought they would be permanently live myself run directly from the ignition. Wouldnt like to rely on remembering to switch them on
before trusting them to stop me (or more importantly the missus) driving into the car in front.
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graememk
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| posted on 27/3/08 at 09:54 AM |
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mine are on all the time...
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hughpinder
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| posted on 27/3/08 at 09:56 AM |
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I would have thought the reversing ones are activated by power in the reversing light circuit, otherwise you'd get the warning beeps when the
guy behind you at the lights is too close....
I don't know how you'd sort the front ones to be only on when appropriate (only when you're in 1st perhaps?)
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martyn_16v
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| posted on 27/3/08 at 10:08 AM |
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quote:
Originally posted by Paul TigerB6
Wouldnt like to rely on remembering to switch them on before trusting them to stop me (or more importantly the missus) driving into the car in front.
I've got these amazing contraptions called 'eyes' that let me know when I'm about to hit a large object. They're great
things, on all the time, and they're portable so I can even use them out of the car. You wouldn't believe the amount of uses I've
found for them over the years. Everyone should have a pair IMO
A 555 monostable circuit (google it, there's hundreds of novice-friendly pages) will do what you want with regards to a push button and timed
output. Use the output of the 555 circuit to drive a small relay to switch the power to the sensor on/off.
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02GF74
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| posted on 27/3/08 at 10:22 AM |
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seconding what ^^^ says.
If you need a parking sensor on the front then you shouldn't be driving.
What about one on the roof when you need to drive under extra low bridges or car park barrirrs?
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balidey
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| posted on 27/3/08 at 10:38 AM |
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Parking sensors are a really useful aid.
Get that last bit... AID, they are not going to be used purely alone to park, my wife is used to diving small cars and she test drove a people carrier
at the weekend and she could not tell easily where the front and rear of the car were.
She has never hit any stationary objects while parking. Neither have I, well, OK once in a works van , but a parking sensor would have been ideal
then. So thats why I'm thinking about getting one.
Surely because I want to improve the safety of our driving standard then thats a good thing?
How do I disconnect the airbag and ABS, as I will not be using these as my eyes will tell me to avoid all ice patches and accidents
EDIT: Martyn, thanks for the info on the 555, i'll have a look and see if i can figure it out.
[Edited on 27/3/08 by balidey]
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jlparsons
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| posted on 27/3/08 at 10:54 AM |
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I agree, parking sensors are very worth having for anything bigger than a supermini, I believe the best thing for the front is for them to be always
on or linked to first gear?
Just had a thought - the only slightly worrying thing with having the front sensors powered on permanently is that there's a possibility that
their annoying beeping will be the last thing you'll ever hear... 
[Edited on 27/3/08 by jlparsons]
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martyn_16v
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| posted on 27/3/08 at 10:55 AM |
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Oh don't take my rant too seriously, it was more aimed at the way I read Paul's post implying utter reliance and that if the sensor was
turned off you *would* hit something
New-ish Audi's have the front sensors on all the time until you push a button to turn them off, and my god it's annoying in a traffic jam.
Unless you want to turn into a homicidal maniac the first time you hit rush hour you really need to be able to shut the thing up.
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balidey
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| posted on 27/3/08 at 11:39 AM |
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Nothing been taken seriously guys
I'd rather get sensors fitted as soon as we get the car than after a few weeks when the bumpers are scuffed to hell 
I like the idea of a switched feed, then you only put them on when we need them on.
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jollygreengiant
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| posted on 27/3/08 at 11:40 AM |
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Peugeot 406 & 806 turbo diesels have glow plugs that operate for 2 minutes AFTER the warning light has gone out. This might be a starting point
for getting your timer.
Beware of the Goldfish in the tulip mines. The ONLY defence against them is smoking peanut butter sandwiches.
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BenB
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| posted on 27/3/08 at 01:43 PM |
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A 555 monostable driving a relay will do the trick. 555's will drive quite a hefty current to so unless you're driving a humungous relay
you won't need a transistor either.
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BenB
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| posted on 27/3/08 at 01:45 PM |
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I think you'll find this would do nicely
http://www.eleinmec.com/article.asp?4
Even gives the cost of the circuit (£3.91)
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balidey
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| posted on 27/3/08 at 02:21 PM |
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I found that site earlier today too. Looks like it will do the job. I even checked the current drain on the sensors and its under the 200mA so I
won't even need a relay.
I'll have a chat with the missus and see what she thinks.
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blakep82
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| posted on 27/3/08 at 02:45 PM |
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hmm, probably said before, permanent live from the key switch, and you shouldn't hear a peep out of them until you're parking. unless you
have a thing for tailgating, in which case you deserve them shouting at you
________________________
IVA manual link http://www.businesslink.gov.uk/bdotg/action/detail?type=RESOURCES&itemId=1081997083
don't write OT on a new thread title, you're creating the topic, everything you write is very much ON topic!
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britishtrident
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| posted on 27/3/08 at 02:47 PM |
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Advise at least 4 sensors on the rear --- if you get a 6 sensor kit fit two of them at a different level so they cover low car park barriers when up
close.
Make sure you get a kit that includes the exact size hole saw.
With rear sensors for psychological reason fit the bleeper in the rear. Fancy displays don't help much except while you are getting used to
judging distances from the bleeper.
If you fit front sensors it might be more sensible to fit a distance display type and switch off/discconnect the bleeper.
http://parkingsensors.co.uk/?source=gpsv&gclid=CMjk7IHDrZICFQ8gQgod3w2dRw
Shop around on ebay for prices
[Edited on 27/3/08 by britishtrident]
[Edited on 27/3/08 by britishtrident]
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britishtrident
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| posted on 27/3/08 at 02:51 PM |
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quote:
Originally posted by blakep82
hmm, probably said before, permanent live from the key switch, and you shouldn't hear a peep out of them until you're parking. unless you
have a thing for tailgating, in which case you deserve them shouting at you
Trouble is at the traffic lights -- many parking sensors start working at over 1 metre
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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balidey
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| posted on 27/3/08 at 03:26 PM |
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Just been checking out the details in the website you just posted. Seems some kits advise fitting a switch for the front sensors so you can turn them
off.
But they work on the brake switch, so I guess they must have a timer system built into the proper kits anyway.
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