Electrical noise problem solved (HK Drive+Play)
 

I thought I would post a message in here in the event that anyone else is having issues with their Harman Kardon Drive+Play iPod adapter.

I started a thread a while back (December - see link below), and I finally got tired of listening to the incessant whine that is present while I listen to my iPod through the Aux input.

https://www.greenhybrid.com/discuss/...ad.php?t=11603

In that thread, jdenenberg posted a suggestion to try building an op-amp based device that would help to fix the impedance mismatch between the devices. I didn't really want to do this since it seemed like a difficult way to fix what should have worked properly in the first place.

Well, I finally caved in and bought the parts at Radio Shack last week and built it. I included a 12V relay in the package to help extend the 9v battery life, so this design needs to tie into the car's 12v accessory power. When the car is turned on, the relay is tripped, energizing the op amp's +9v and -9v supplies. When the car is off, the circuit is dead... I mounted it in a plastic enclosure with "in" and "out" 3.5mm stereo jacks, and a power adapter that I can disconnect if needed for removal from the car. Total cost was about $30 if you include the 12v connector and a 6' 3.5mm audio cable I used.

To mount it in the car, I just put it in the armrest storage area, and I drilled a 5/16" hole in the front of the armrest storage bin to route the power wiring and the in and out audio cables. I spliced into the 12v power socket's wiring to get the needed accessory power.

When all was said and done, it really worked! I posted pictures of the device and the installation in the gallery here.

I just want to thank jdenenberg for making the suggestion and answering questions!

Links below:

https://www.greenhybrid.com/share/sh...hp?i=2453&c=40

https://www.greenhybrid.com/share/sh...hp?i=2454&c=40

https://www.greenhybrid.com/share/sh...hp?i=2455&c=40

https://www.greenhybrid.com/share/sh...hp?i=2456&c=40

https://www.greenhybrid.com/share/sh...hp?i=2457&c=40

https://www.greenhybrid.com/share/sh...hp?i=2458&c=40

https://www.greenhybrid.com/share/sh...hp?i=2459&c=40

https://www.greenhybrid.com/share/sh...hp?i=2460&c=40

Jeff

Re: Electrical noise problem solved (HK Drive+Play)
 

Cool.