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Wiper delay circuit


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Has anyone fitted a reasonably simple wiper delay circuit to a small chassis car, possibly based on the compound relays fitted to land Rovers. 

I'm thinking of moving the dip/main/flash switch elsewhere on the column and re-using the existing one/location for a wiper switch, with the flash used for an electric wash pump. As that switch has 3 positions for lights, and the flash, I though I might use the first for off, the second for delay, and the third for normal op. The existing wiper switch location might then be used for a potentiometer to control delay/speed.

I know I can put a circuit together to do the delay, probably based on a 555 timer chip. But if there's a rugged automotive device I can use easy enough, that's got to be better. However, I can't find the circuit for the Land Rover showing how the relay wires, and what value the pot, that I assume controls delay, might be.

Graham

 

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More years ago than I care to remember, One of the "motoring" magazines published a circuit to do what your asking using Transistors various compenentry and vero board!, (remember that, lots of holes to solder your components to?).

Google has several "answers"?. I just put in :- DIY time delay for Windshield wipers?

Pete

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There used to be a DIY kit available from Maplin Electronics that was easy to put together and only cost about £15.  I built one for my Spitfire and it works very well.

As you may know, Maplins closed some time ago but there may be a source of the same kits elsewhere?

EDIT.....   Looks like they are still trading online.  See Maplin - K2599 Intermittent Wiper Controller - Special Savings Today at Maplin Direct with UK Direct Sale 

Bargain at £12.99

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It's hard to be sure, but it looks like there's a pulse generator and relay all built into the units used on Land Rovers and such, the unit being like £5 to £10 on ebay. I think, if I've got it right, all that needs is a pot to control that generator, some wires, and some Lucar connectors, and it should run the wiper motor direct.

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Pin 15 looks like +12v. 53M looks like drive to the motor. 31 looks like ground. 53S might be connected to a park switch, perhaps. I think then, that I and T go to a pot to set the speed/frequency of pulses and the trigger switch.

It will need a small mod to a herald 13/60 column switch to separate the flash from the main beam output, but that looks easy enough.

The problem is in finding the circuit and the resistance value and power requirement for the pot. If it needs a big wirewound one, like is used as a dimmer on some dashboard lighting systems, then it's probably not worth it, and I'll just get a relay and a 555 - I have Veroboard.

I do remember discrete transistors (we did valves at A level when I were a lad - my physics teacher worked on the first radar laid AAA and claimed to have known A.C. Clarke before he were famous; even before he wrote Glide Path), but a timer chip and a relay will do better if I must build something (I'm not paying £36 for a blooming low frequency pulse train generator).

Graham

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Back in the good old days we used to make our own; 'we' being a group of teens and twenties who used to make our own lightboxes and liquid wheels for discos, build our own LED watches from kits etc. I usually watched and handed over screwdrivers or tape etc.

One of the guys made this unit for an MG Midget, which has a variable speed option; it's still sitting on my shelf but hasn't been tried in many years. No doubt highly advanced for its' day!

wiper.JPG.4bd5f24197a67b220410439079c7ca44.JPG

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15 hours ago, Sparky_Spit said:

There used to be a DIY kit available from Maplin Electronics that was easy to put together and only cost about £15.  I built one for my Spitfire and it works very well.

As you may know, Maplins closed some time ago but there may be a source of the same kits elsewhere?

EDIT.....   Looks like they are still trading online.  See Maplin - K2599 Intermittent Wiper Controller - Special Savings Today at Maplin Direct with UK Direct Sale 

Bargain at £12.99

That kit works well. You can also put the timer pot on a fly lead so that the circuit can be hidden away somewhere convenient.

I wouldn't go near the 'smart screen' unit. Too many folk have said how iffy they are.

 

Roger

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If I was looking at building a module with variable pulse rate - I'm assuming that pulse duration isn't very important, as long as it's not too long, because the wiper motor self powers until it returns to park -, then I'd look at modifying one of the 555 pulse train generator PCBs on ebay for less than £5 from UK suppliers. That includes ones where there's a pulse width control. A mod would be needed because they only seem to go down to 1 Hz and this circuit probably needs something like 1/60th of a Hz, maybe a bit less, to something around 1/2 or 1/4 of a Hz. I expect that would be just a case of adding a cap in parallel or replacing one with a larger one. I've a fair selection of medium sized ones leftover from building some crossovers that will probably do. The circuits, or one near enough, should be available on line somewhere. I'd get it right with a LED on the output. It would also need one of he pre-sets changing for a pot on flying leads. I haven't looked at mounting that in the hole where the wiper switch/pump fits, but I expect it can be done with the right sized washers, etc.

But I still wonder if the Land Rover unit gives a usable intermittent rate even if it's not adjustable. That should be a fairly easy installation between the switch and the motor, with or without the wipe on wash connection.

Graham

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1 hour ago, SpitFire6 said:

use a PIC chip/IC cheaper than a NE555! Program with ladder.

Seems improbable, given the 555s on a board with all the caps and trimmers to run down to 1Hz are as little as £1.99 inc. P&P from the UK: https://www.ebay.co.uk/itm/265241859968?hash=item3dc1a59780:g:jUsAAOSwSjJg~TXD.

I admit I'll have to do some trial and error to find the right cap value so it runs 60 or 100 times slower, and then solder in that cap and the leads to a dash mounted pot. But I bet I'd have more than that to do in making a microcontroller drive a relay in pulses at a rate set off at remote pot (A to D?), even if I get one on a board that will take 12-15V.

Can it be done with clockwork?

Graham

 

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I've ordered one of them 555 pulse generators. At £1.99 its cheap enough to see if I can get it to run with a space of a min or so, and a mark less than the time to sweep the wipers in a proper deluge. Otherwise it would sweep several times at normal speed for each pulse.

It'll want a transistor added on the output to drive a 20 or 40A relay. But that won't be hard to wire in circuit.

Graham

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