Building a Recessed Wiper Delay

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e129745

Joined Aug 8, 2013
1
Hi,
I want to add intermittent wiper control to my 1968 Olds Cutlass. The challenge is they are recessed blades or they park below the hood line when wiper switch is turned to off.
A typical adjustable wiper delay works, but the blades cycle down into the park position at end of each run interval if a long enough delay is used and the wear and tear not needed nor welcomed on a 45 year old classic.
I want to connect something that:
Interrupts the 12VDC supply (or ground?) for a variable duration, and resume power again. Like turning the key off during wiper sweep, then back on again. I will time when the unit cuts power to wiper motor by positioning a small magnet towards the outside diameter on the main gear of the wiper transmission. 1 revolution of gear makes 1 full wiper cycle, (over and back). With an adjustable position NO/NC reed switch mounted, it will be activated by magnet when blades are in lowest position on windshield.

The delay needs to open a relay, disconnecting the motor from the 12VDC source and start delay countdown. At end of delay duration the signal to relay coil is resumed thus operating relay and reconnecting source to wiper motor, even though the reed switch triggering start delay is still sending trigger signal, as magnet will still be activating reed switch.

I think the delay can work either providing voltage to relay coil at run or denying voltage, since the relay will have both NO and NC connections. I have also ordered a reed switch with both NO/NC ability, just in case. I intend to turn on low wiper switch and choose to turn on/off delay unit and adjust pause time at dash.

Essentially, this should be a simple industrial logic exercise, but I'm finding I know less about this than I thought , but both the components and availability has changed in the 25 years since I had anything to do with the maintenance/operation of this kind of equipment. I thought to build some circuit with a 555, but haven't found anything that would work, especially with the magnet/reed switch in trigger state.

I appreciate any help, I hope others will find this helpful in the future as well.
Patrick
 
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KMoffett

Joined Dec 19, 2007
2,918
I did a Google: Parked wiper delay circuit

Found this at https://groups.google.com/d/topic/sci.electronics.design/sNEvk1CSSP8‎

Youngster ;-) But on-track!

What I did around 36 years ago was to shunt the "park" switch with an
SCR.

Pulsing the SCR turns it on and starts the motor.

As soon as the mechanism leaves the "park" position, the "park" switch
conducts, resetting the SCR.

The mechanism does one sweep and stops, waiting for a new pulse from
the SCR.

Since the voltage across the "park" switch pops up to Vcc when the
"park" position is reached, this voltage can be used to restart
whatever timing scheme you use for determining "pause". (Suitably
filtered, of course. It's a "ratty" environmental.)

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WBahn

Joined Mar 31, 2012
29,978
Unfortunately, discussions involving automotive modifications are not allowed under the ToS for this forum. You can expect this thread to be closed in pretty short order. But the closing post usually contains a link to a list of other forums that welcome such discussions.

Good luck.
 

bertus

Joined Apr 5, 2008
22,270
Hello,

I am closing this thread as it violates AAC policy and/or safety issues.

Quote:
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There will be enough sites where automotive questions can be discussed :
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Bertus
 
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