Intermitent wipers

[minor_hickup]

Has anyone fitted an intermitent wiper kit from maplins or similar? I have built the PCB but have no idea how to fit it!

[Pyoor_Kate]

I built up the Maplin PCB - but I discovered that the spike from the wiper was enough to zap the 555 timer in mine, so I suggest that you drive it fairly directly from the battery, I took my 12v feed off too close to the wiper motor supply (i.e. the switch....).

Um, other than that it should work.

[minor_hickup]

Ny ideas as to what connects to what? I can't make head nor tail of the instructions. It seems i have to figure where to connect bits on the circuit by using the diagram rather than simply saying "connect the feed to terminal A".

[alex_holden]

If you post a scan of the diagram we can try to make sense of it for you.

[dp]

I might be able to help, are there 5 terminals at one end and adjustable resistors - adjusted by screws?

If so, one adjustable resistor will control amount of time power goes on for and the other, how long power stays off for.

The five terminals are (in no particular order)
power for the circuit itself (+)
earth for the circuit itself (-)
power for the thing being controlled (in our case the wiper motor) (+)
normally open (disconnected) terminal (no)
normally closed (connected) terminal (nc)

It's probably simplest to experiment with a 9v battery and bulb:-

connect one end of the battery to the power for the circuit <i>and</i> the power for the device.
Connect the other end of the battery to the earth terminal.
Connect one end of the bulb to the normally open (no) terminal and the other to the battery earth.

If I've got the circuit right the bulb should come on for a set time and go off for a set time. Try playing with the variable resistors until the light comes on for about a second then stays off for as long as you want the delay.

Once connected to the wipers, the wiper return wire (sorry, not idea what colour) would be spliced to the normally closed circuit. So, when the circuit is energised, the one second of power gets the wiper going power the switches to the wiper return wire which brings the wiper back. And this repeats as long as the circuit is energised.

Sorry, I've probably explained badly, I don't have the circuit to hand. In any case see how far you get with a battery and bulb and come back with more questions.

[Pyoor_Kate]

Mine I had to do some experiments with - because it's designed for a motor with - uh - more wires; it has some sort of short term latching thing going on so as to make sure the motor doesn't switch off again before it wipes. But, my brief tests on *my* wipermotor were enough to tell me that it'd work without having to work out how to wire that up.

It, as I recall needed a 12v feed - so something from the fused ignition switched side (but as far away from the wiper circuit as you can get, I suspect). And it also needed to, essentially, bridge the wiper switch - i.e. mine needed to act in parallel with the existing switch. But then mine blew up so I might not be the best person to ask.

[bmcecosse]

My wipers are intermittent already. Switch on - wiper arms move from left to right on the screen - pause slightly - then move back from right to left - pause etc etc. So the movement is already 'intermittent' - works fine for me. Why bother to make it more complicated ?

[woo]

I made mine from a circuit that was published in a 1989 copy of minor matters. While it may not be exactly the same as yours, describing how mine works may help.

It uses a relay that is triggered by a 555 timer. The circuit has 2 variable resistors. one to adjust the time of the relay pulse. This makes sure that the wipers will start and automatically park, and one with a knob that you turn to get different sweep periods. This variable resistor incorporates an on/off switch. Mine works between zero and a 15 second dwell and is sited beneath the dash board. the device is connected via 4 wires. 1 live from the fuse box. 1 to earth. The other two connect to the two screw terminals on the existing wiper switch, and are thereby connected to the wiper motor.

I should imagine that they all are connected in a similar fashion.

I found 2 things using mine.

1. The coil and the dynamo needed radio suppressors fitted, else they would trigger the delay at random.

2. The 555 timer takes 1/2 of the desired dwell time before it starts working, so, if I want a 12 second dwell it takes 6 seconds before the first sweep. After that it is 12 seconds. I get round this by starting the delay unit while my wipers are working normally, then after a short while turning off the normal wiper switch.

I hope perhaps this helps

[minor_hickup]

I've just got in from work, this is a bit mch to think about so I'll have a think tomorrow and try and get some pictures of the diagrams.