Jump to content

Wiring schematic for 2-input mixer

Cali Kid

Recommended Posts

Hey all, I have been looking for a simple way to mix two audio channels one monaural from my radar, the other stereo from my player.

I saw one that sean Daly had made some time ago, but no more. I have also foumd some schematics online that work for line level inputs.

The design is simple enough, I'm just not sure which resistors to use to achieve the correct impedence with my earbuds. I've really forgotten my electronics training big time confused.gif

And I want to include a couple micro potentiometers to control inputs individually.

Any ideas?

Link to comment

Have you tried contacting Sean about this? I just took apart one of his mixer's to check for you but was unable to read all the numbers on each of them. I can tell you that he used four resistors total inside the unit, two per channel, one stereo & one mono outputs.

If you get it together, post up what you used. I've thought about making up another one and if the pots work in the system without damaging the earphones that would be a plus.

I'm sorry Sean decided not to continue making these things for us. They were a whole lot cheaper than the Mix-It type and a lot smaller.

Good Luck

Link to comment


if you can make out the color bands of the resistors It will tell me the ohm rating. Most resistors aren't numbered, just color coded. Or... a simple test with a multi-meter will reveal the impedeance.


And ya, I just emailed sean.

Link to comment
Jerry Johnston

Why reinvent the wheel even though you're capable? Radio Shack sells a three channel mixer that uses two AA batteries. Catalog #33-1109 - I think I paid $20 for it. I do have a RS book that shows the diagram of a 4 ch mixer that is simple to build if you still want to build one. It's easily adaptable to a two channel. The book is dated 1979. If you pay the postage I'll send it to you.

Link to comment

Thanx for the info Jerry, but that splits the output.

I want to mix two inputs to one output.


I'd like to fabricate my own. so as to make it small as possible. Just need some numbers. I spent a good amount of time reviewing electronics tutorials last night dopeslap.gif

Getting close

Link to comment
Jerry Johnston

My bad, you're right the RS unit is one input and 3 outputs however the schematic is for two or more inputs with 1 output. It uses a HEP801 and a HEP50 and is a very simple circuit. If you think the transistors are available yet and would like me to scan the circuit let me know. It also shows a mixer using 2N3819 transistors one for each of three inputs and one for the output.

Link to comment

Guys - sorry for the hijack - I've been using one of Sean's 2-way units for a while. First on my '02 R1150R with a V1 and XM. Worked great, no problems. I moved the setup over to my '05 R1200ST (many of you have seen pics) and also mounted a Garmin Quest (I don't normally use the audio on the Garmin). XM sound quality is great into my ER-6i's, no issues. However, when I plug the V1's audio output jack to the mixer I get a low volume whine which is easily drowned out by a moderate listening level on the XM. I get this sound even if I just touch the male plug on my patch cable to the metal ring on the V1's output jack. If I substitute the Garmin mono output for the V1, same result.


I tried using a Boostaroo (same unit as the Radio Shack product in Jerry's post above) and the output is a lot louder, but so is the whine. I thought maybe this gadget would have a filter...


Any ideas as to what is causing the whine ? Can I fix it ?

Do I need to go to a MixIt ? Does that have some kind of noise filtering capability.


Thanks guys !

Link to comment

Thanx again Jerry, I looked for the HEPs. They aer around, but I'd like to use radio shack ready components in case of need to modify. I've been browsing the web and have a few good ideas to try. Gonna buy a couple trimmers and play with the settings, see what works best.


The main problem is that I have no idea what the output is at the jack of the radar detector. It is very poorly controlled with the external speaker setting. It is so loud, even all the wway down. Got to call beltronics again tomorrow. Cd player is easy.


I saw the Mixit, but that is more than I need, larger and more expensive.


I'll pony up the schematic when I get it all figured out.

Link to comment


This topic is now archived and is closed to further replies.

  • Create New...