# B6/B7 Funk switch - Converting momentary switch to latching switch DIY



## 804 mini (Feb 24, 2014)

I couldn't find a good guide for converting the B6/B7 Funk switch into a latching type switch, so I'm documenting how I solved the problem.

What is the funk button - Its a button used by German police to switch between their 2-way radio and conventional radio. More importantly its a button that says funk on it and has OEM fit.

Problem - The B6/B7 platform funk button is the momentary type and most useful applications require it to be latching. Momentary switches are ones that complete the circuit only when being depressed (like your car horn). Latching type switches are on when pressed and need to be pressed again to turn off (like a computer monitor power button). 

My use for this switch was to power a secondary fuel pump and I didn't want to hold the button down for ever to keep the pump running. 

To solve this issue I used a momentary to latching converter from The custom saber shop website (they make stuff for flashlights) has a really small converter that does everything needed. Part number is POLAV. Be sure to buy the "high voltage" model (2.2-16V). It contains all of the electronic wizardry for the conversion.

Another issue is that the funk button and converter can not support enough current for my application (~12A). I didn't see a spec listed, but the wire size on the funk switch implied more lights-type applications and less load carrying. Using a relay to power the pump was necessary in my application. This circuit is only to send the on/off signal.

Wiring diagram
+12V is supplied to position Vin on the converter and position 1 of the funk button (funk back lighting). I used my radio power wire since it's only on when the key is turned.

Vout from the converter goes to the fuel pump relay and to position 2 of the funk button (LED power). This way you can verify that the led turns on/off 

Funk switch position 3 (grounds LED and backlight) and converter GND to ground. The converter needs to be grounded to "remember" its position, learned that the hard way.

Funk switch positions 4 and 6 go to converter positions A and B. This sends the signal from the switch to the converter.


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