I know this subject has been beaten to death, but I can't find specifics. Customer wants to add a phono plug to their 40-180. Ron posted a schematic a looooooong time ago, but it doesn't seem to be accessible.
What's the best way to do this? And no, they don't want to use a transmitter.
Pat
One other quick question, Ron. Am I correct in assuming that this method would eliminate the need for the spdt switch that Dale mentioned?
Let's just repost that modified 38-40 schematic here for clarity.
![[Image: 3840mod.jpg]](https://philcoradio.com/images/phorum/Phorum_Stuff/3840mod.jpg)
This mod uses a closed circuit 1/8" (3.5mm) stereo jack instead of an RCA jack. The jack takes care of the switching so you are correct, no additional switch is needed with this design. Just make sure you wire it up correctly.
I believe the 1/8" jack was chosen to not only provide the automatic switching, but also to better match the input from an iPod or other MP3 player. You can also use this to add Bluetooth capability to your radio.
As always, your help is invaluable. Thank you!
Phones must be terminated with a 100 Ohm resistor in each channel. Bluetooth needs 1000 Ohms in each channel.
Could you expand on that? Thanks.
Left and right channels must be added to together since you do not have a stereo input. See attached:
So how would that then affect Ron's schematic?
There are three terminals on the 1/8 in. jack. One is for left and one for right. Put one resistor on each and connect the two loose ends together, then attach capacitor. Third terminal is ground. It is less complicated than Ron's schematic shows.
Thank you, sir. Much appreciated.
Pat
Yes but, the idea behind Ron's circuit is that it automatically disconnects the radio's audio when connected.
Steve