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GS guy
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 Posted: Sun Dec 29, 2019 1:57 pm Post subject: 6V Wiper Wiring - SPST switch? |
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Another wiring question to jog the egg-nogged brain.
The givens: A 6V single speed wiper motor fitted with a 12V armature, using a SPST switch to activate the wipers (matching the other dash switches), trying to design my power distribution so that most of the auxillary relays are ISO 280 micro footprint so I can use sealed power distribution modules. I've only found these relays available in SPST and SPDT formats.
Using this wiring diagram for the single-speed wiper motor:
As I understand it, the switch shown appears to be: 1) a rotary switch, and 2) a DPST type switch. That is, it has two independent switches connected mechanically so that only 2 poles around the perimeter can be connected at any position - either 31b to ground (off) or 54 to 54d (on).
The hat trick - how to switch the wiper motor with a SPST switch?
My thinking on this:
Option 1: Use the SPST switch to (when on) apply power directly to 54d as in the rotary switch, and also activate the coil of a SPDT relay. The relay is wired with NC terminals connecting 31b to ground - so it would open when switched on.
Option2: Use 2 SPDT relays so that the switch activates both relay coils, relay 1 applying power to 54d across NO terminals, relay 2 operates as detailed in option 1.
I'd rather not have to use 2 relays, but have a concern option 1 may provide a "momentary" short to ground the instant it is switched on? My feeble brain has a hard time seeing the dynamic flow of electrons in the first milliseconds of current flow! 
Jeff
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Dale M.
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| Posted: Sun Dec 29, 2019 5:05 pm Post subject: Re: 6V Wiper Wiring - SPST switch? |
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Different diagram, but same concept...
Dale
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EVfun 
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| Posted: Mon Dec 30, 2019 1:41 am Post subject: Re: 6V Wiper Wiring - SPST switch? |
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I think you can use a SPDT relay to operate single speed wipers. This isn't a pretty text drawing but the idea is that the wiper motor constant connection is connected the the moving arm of a SPDT relay. It can be connected to power to run the motor or ground to quickly stop the motor. The relay can be held on either by the SPST switch for the wipers or by terminal 54 which will receive power from 54d via the cam contact only when the wipers are supposed to run.
The top 4 terminals shown on the left edge are the wiper motor terminals. The "+" is the fused wiper motor power supply. The two SW terminals are the dash wiper SPST switch. NC means no connection. Grounds are shown wherever they happen to land. Hopefully you can make out the relay coil and contacts.
| Code: |
31 --- GND
54 ------------------>|-------
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31b --- NC GND ---o |
/ |
54d --------------/ |
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+ -------------o----o |
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| (----o---o---------------
SW ------------o ( |-->|<--| |
(------------o--- GND |
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SW ------------------------------------------
->|- small diode such as a 1N4001
->|<- bidirectional TVS diode such as 1.5KE24A
The TVS may not be required if a 1000 volt
1N4007 diode is used. |
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GS guy
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| Posted: Mon Dec 30, 2019 12:55 pm Post subject: Re: 6V Wiper Wiring - SPST switch? |
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EV - I'm afraid your diagram is may be over my head (to follow)? Hard to tell what "moves" like when the switch is on/off. I tend to think of diodes as being circuit board components, hard to wrap my head around wiring one in-line?
Dale - That's the 2-speed version, with the also confusing wiper switch diagram. I'm guessing the 2 parts of the switch as shown have a mechanical connection, making them move as one.
After more searching I did come across a 3rd option, this one posted by jspbtown during the build of his awesome orange buggy a number of years ago. Had to re-ID a couple of the connections as the 2-speed and single-speed motors are labeled differently, though the functions are the same. Here's a diagram matching my single speed wiper motor:
In this case just switching power between 54d and 54 on the motor, 31b is left disconnected (I'm not sure what 31b did anyway in the OEM diagram, seems to only ground the other side of the motor when the switch is off?). jspbtown used this circuit to drive one speed on the 2-speed motor used in his build and apparently it worked fine.
Also may be scratching my idea of using the micro 280 relays and relay box - at least for my under-dash stuff. Trying to avoid using a bunch of seperate fuse boxes, relays/boxes, terminal strips etc. Plus I really want to use a dual 87 pin outlet relay for 4-way flashers, and liking the slightly larger format "Mini" relays for higher amp stuff - fuel pump, driving lights. Ordered this box from Amazon: https://www.amazon.com/gp/product/B07ZNFN42Z/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
it should do most of what I want in one package?
Jeff
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EVfun
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| Posted: Mon Dec 30, 2019 2:26 pm Post subject: Re: 6V Wiper Wiring - SPST switch? |
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Buggies typically have fairly long wipers so the diagram from jspbtown may work. The purpose of the stock system switching of 31b to ground is so the motor is shorted to itself when the wipers need to stop. Shorting a motor is a way to make it stop turning quickly. I had a Bug before where that wire was broken and had to shut the engine off (voltage dropped from about 7 to about 6 volts) to park the wipers. With the engine running they would slow at the bottom, but coast just enough for the cam to get past the park position and power the motor again through terminal 54.
I'll make another try at the wiring diagram from before. This time I'm only showing the wiper motor connections being used for this circuit. In a fiberglass body buggy you will have to provide the wiper motor a ground connection. The lines ("-" and "|") represent wires and the "o" represents a connection or contact. The relay terminals are numbered now and the drawing generally cleaned up. If you use a ISO 280 relay it should come with built in coil suppression, so that eliminates the need for the TVS diode.
| Code: |
1N4007
W M 54 o----------->|----------------|
I O |
P T 31 o----o GND o----o 87a |
E O / |
R R 54d o------------/ |
30 |
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+ fused o----o-----------o 87 |
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| 86 (-------------o
| ( |
SWITCH / ( |
SPST / o ( |
| 85 (----o GND |
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|-------------------------| |
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EVfun
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| Posted: Mon Dec 30, 2019 6:21 pm Post subject: Re: 6V Wiper Wiring - SPST switch? |
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Hmm...
I have an idea for my "relay logic" that may eliminate that one diode. Let me scratch it tonight and I'll post back if it can work without any short circuit modes. The posted method only needs that diode if the switch is turned on when the wipers are not on the park part of the wiper motor cam.
EDIT:
The idea to ditch the diode was a big NO. That is why it is important to sketch things out and check each possible combination.
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| As a general rule, cheap parts are the most expensive parts you can buy. |
Last edited by EVfun on Mon Dec 30, 2019 10:46 pm; edited 1 time in total |
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Q-Dog
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| Posted: Mon Dec 30, 2019 6:32 pm Post subject: Re: 6V Wiper Wiring - SPST switch? |
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What is the relay for? My 2 speed motor doesn't use a relay. Just a simple 2 position switch.
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GS guy
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| Posted: Mon Dec 30, 2019 6:42 pm Post subject: Re: 6V Wiper Wiring - SPST switch? |
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That's a little easier EV, but not seeing how 54 is getting power with switch off - to complete the park cycle? I can see how you've provided the 2nd gnd path for the motor through the relay (when switch-off) - that's neat! The diode (direction) prevents current going 86 to 54, but don't see where that helps or purpose? Maybe I'm missing something?
Seems like 54 needs 12V constant, and the diode would go between 54d and 30 to prevent shorting when the motor is not in the parked position?
On the relays, yes - I will be using resistor or diode (across the coil) type relays for V surge suppression.
Jeff
OK, stepped away - now I see it, the diode prevents a short from 54 to 54d to gnd through relay when the switch is turned on and wipers not "parked". That makes sense now, but still not seeing how park works when switched off?
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Last edited by GS guy on Mon Dec 30, 2019 7:30 pm; edited 2 times in total |
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MrGoodtunes
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| Posted: Mon Dec 30, 2019 7:13 pm Post subject: Re: 6V Wiper Wiring - SPST switch? |
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| Q-Dog wrote: |
| What is the relay for? My 2 speed motor doesn't use a relay. Just a simple 2 position switch. |
A 2-position switch? Mine has 3 positions: High, Low, Park
This may be no real help, but... Since I found success using a VW switch to operate Fiat wipers, you'll probably find success too.
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GS guy
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| Posted: Mon Dec 30, 2019 7:25 pm Post subject: Re: 6V Wiper Wiring - SPST switch? |
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Yep - any DPDT switch will do the trick. Too easy though... 
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GS guy
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| Posted: Mon Dec 30, 2019 7:51 pm Post subject: Re: 6V Wiper Wiring - SPST switch? |
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Dang - now I think I see it EV! The motor park switch (out 54) provides power to the relay coil to keep it running until it parks - at which point power is cut to the coil, relay opens and motor 54d is grounded! Genius!
Let me re-work my diagram......
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GS guy
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| Posted: Mon Dec 30, 2019 7:52 pm Post subject: Re: 6V Wiper Wiring - SPST switch? |
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Wait a minute - I think I just found a wiper app for my I-phone.....
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Q-Dog
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| Posted: Mon Dec 30, 2019 9:39 pm Post subject: Re: 6V Wiper Wiring - SPST switch? |
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To clarify: I use an on-off-on toggle switch, so two on positions. One side is high speed, one side is low speed. Switch it off from either position and the wipers park.
Of course, I haven't actually used the wipers in years. I assume they still work.
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GS guy
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| Posted: Tue Dec 31, 2019 9:57 am Post subject: Re: 6V Wiper Wiring - SPST switch? |
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Q-Dog: is the switch a dual pole model? I'm guessing yes since your park works as normal. My objective is to use a single pole, single throw (Contura V) switch.
Here's the new simplified diagram with EVfun's improvements. I like how this one works (opposed to my earlier attempts) since it maintains full park function and grounds both sides of the motor when switched off and parked. The diode supports 1A forward current which is plenty to run the relay coil. Sweet!
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EVfun
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| Posted: Tue Dec 31, 2019 12:10 pm Post subject: Re: 6V Wiper Wiring - SPST switch? |
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So much more readable than my ascii art. I see something interesting about the way you show 2 separate 12 volt sources. If the +12v fused is a constant hot the wipers would continue until parked if you turned the car off with the wipers running. One VW bit I found interesting is that the wipers on the oval window Bugs are powered by a constant hot so they can operate with the car off.
If you are using SPST switches how do you plan to handle the headlights and parking lights? Just an idea, a SPST light switch could power the tail lights and terminal 30 of another SPDT relay. Ignition switched 12 volts could power terminal 86 and 85 could be to ground. Terminal 87 could go to the headlights and terminal 87a to the front parking lights. You would have headlights and tail lights if the car was on and parking lights all around if the car was off.
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GS guy
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| Posted: Tue Dec 31, 2019 2:07 pm Post subject: Re: 6V Wiper Wiring - SPST switch? |
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I guess if both feeds were wired from an ign-on switched source it might defeat the auto park function if the ign was switched off before the wipers parked? Next time the car was switched back on/started the relay would be off and you'd have to turn the wipers back on & off again to get them to park? Hadn't thought of that!
My headlights will be from the supplied American Autowire GM style (vintage) headlight switch, with the old rotary dash light dimmer! How many people remember those!?? It'll be going through the VW dimmer relay though to maintain the dimmer function on the turn signal lever. I'll try to disguise it with a different knob!
Thanks for the wiring ideas EV!
Jeff
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EVfun
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| Posted: Tue Dec 31, 2019 2:33 pm Post subject: Re: 6V Wiper Wiring - SPST switch? |
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| GS guy wrote: |
I guess if both feeds were wired from an ign-on switched source it might defeat the auto park function if the ign was switched off before the wipers parked? Next time the car was switched back on/started the relay would be off and you'd have to turn the wipers back on & off again to get them to park? Hadn't thought of that!
My headlights will be from the supplied American Autowire GM style (vintage) headlight switch, with the old rotary dash light dimmer! How many people remember those!?? It'll be going through the VW dimmer relay though to maintain the dimmer function on the turn signal lever. I'll try to disguise it with a different knob!
Thanks for the wiring ideas EV!
Jeff |
If you use separate feeds as I mentioned before there is one possible risk, depending on the ignition switched power source. That would be the wiper motor, through the diode, trying to power everything else that you just tried to switch off with the ignition key. It really is best to power both from an ignition switched source (like most Bugs) or both from a constant hot source (like on oval window Bugs.)
If you use a single ignition switched source and turn the car off with the wipers running it won't be a problem. When you turn the ignition switch back on the wipers will resume running via the wiper switch powering the relay. If you turned that switch off before restarting the buggy the wipers will remain where they stopped until the wiper switch is turned back on.
I first built that wiper circuit so I could have "mist mode" on my wipers. You can have any number of switches to turn the wiper relay on. One was the switched on contacts of a stock wiper switch and another was a little momentary push button switch that I added under the dash.
My buggy wiring is dead simple, and there are no wipers. I have just 2 fuses, one supplies 12 volts to the ignition switch and the other to the light switch. I use a 4 position light switch (off, parking lights, low beams, high beams.) I have 2 relay circuits. The first is 2 DPDT relays to combine turn and brake lights rear and turn and parking lights up front. The second is 2 tiny SIP relays and a couple resistors to reverse the polarity and add load for the alternator and oil pressure lights.
You're welcome. I'm more than happy to help with automotive wiring. 
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GS guy
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| Posted: Wed Jan 01, 2020 12:02 pm Post subject: Re: 6V Wiper Wiring - SPST switch? |
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| EVfun wrote: |
If you use separate feeds as I mentioned before there is one possible risk, depending on the ignition switched power source. That would be the wiper motor, through the diode, trying to power everything else that you just tried to switch off with the ignition key. It really is best to power both from an ignition switched source (like most Bugs) or both from a constant hot source (like on oval window Bugs.)
If you use a single ignition switched source and turn the car off with the wipers running it won't be a problem. When you turn the ignition switch back on the wipers will resume running via the wiper switch powering the relay. If you turned that switch off before restarting the buggy the wipers will remain where they stopped until the wiper switch is turned back on. |
Thought about this some more and it does seem like the safest way is to wire both 12V inputs from a fused ignition switched source. It just means letting the wipers park before shutting off the car - but seems like a much better bet than leaving 12V constant on a 50+ year old electrical component!
Final revision:
Jeff
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GS guy
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| Posted: Sun Mar 22, 2020 10:08 am Post subject: Re: 6V Wiper Wiring - SPST switch? |
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Bench tested the wiring setup from my previous post - worked like a champ! Motor went solidly to park position no matter where in the cycle I cut the power. Now this is a 6V motor/wiper system I rebuilt about 10 years ago, installing the 12V conversion armature at that time - but was never test run. Been sitting stored away ever since. Sucker ran great, although it seems to run a little fast? No drag of the wipers though, so I'll need to see it installed and running to get a feel for the working speed. I recall on my last ('74) Bug the wipers seemed to run pretty slow, even on "fast" speed.
Since my Deserter buggy will likely never have a top, having wipers is more of a "inspection" feature and probably will never be used? Happy with the bench test though! 
Jeff
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