Intermittant wiper kit

I have built two of these kits, one for my car and one for my son’s. I have just fitted the first and the time between activations is far quicker than you state, the effect is that on the slowest setting wiper runs continuously although you can hear the relays switch on and off about twice a second. Assunming it to be a fault with one of the kits I have fitted the other and it too switches at the sme rate. Please advise what can be done to get back to the stated intervals?

Roger Hirst

Make sure to check all resistors and cap values.
A wrong resistor or cap value will influence timing.
Sorry, this forum does not allow picture uploads
If you can provide LINKS (e.g. by using a free online picture base) to HI-RES and SHARP pics of your assembly (both solder- and component side)
then we can take a look and provide some feedback.

Thank you for your response. I have checked the values against the circuit diagram and found no errors. I am attaching a link for photos of both sides of the board as follows I trust this will help you idetify the issue and get back to me with how I can get the correct intervals.

Regards Regards

Sorry, there seems to be a problem with two pictures, only 50% is visible.

please find attached the link for another picture

Regards Roger Hirst

As far as we can see, assembly looks OK, so at this time, we do not know why it behaves this way.
Do the kits behave this way when the wiper are not connected to the relays?

Both kits behave exacly the same, whether or not the output of the relays are connected or not.


Very strange.
The part that is responsible for the timing is C2.
You could experiment by increasing its value until the desired timing is obtained, or you can return both kits for inspection.

Thank you for your reply, to where do I need to send the kits please?


US residents: please call (817) 284 77 85 for RMA#

Rest of the world:

Velleman Projects Tech. Dept.
Legen heirweg 33
9890 Gavere

You should have recieved my two units by now, please can you advise what the prognosis is and when I can expect them back?

Roger Hirst

After checking with repair dept, they informed us that your items have been treated last week.
Both units have been mailed to your address and should arrive soon.
Problem was solder related.

Thank you for the return of these, I have refitted it to the car and had exactly the same problem, coincidently my son was in the process of changing over the facet fuel pump and as soon as he disconnected it the wiper unit started to work properly. I can only assume that the issue was related to the soloniod operation of the fuel pump as it now does 15, 10 and 5 second intervals as it is meant to do.

Thanks for your help with this, please advise, if you know, what needs to be done to avoid the interferrance, would a capacitor across the pump work?


A couple of things you could try:

A 100nF cap across the solenoid.
A 4700µF cap across the wiper robot supply, as close as possible to the board. Mind the polarity!