> "Kevin & Natalia" <[EMAIL PROTECTED]> wrote: > I have a question regarding the bottom of the > 2 pictures.
The lm-386 circuit found at: http://www.repeater-builder.com/tech-info/pix/link_circuits.gif > 1. If the level of either input is changed, will > this alter the level of the other input? Yes, slightly (a very small amount) > 2. can one add extra inputs to the circuit, I > want to use an circuit that will allow 4-6 > inputs with 2 outputs. Yes, following the informal rules of resistive audio mixing, all the input pots remain 100K, but the wiper (center) lead resistors become 1/2 the pot value (50K). If that scares you, change the 10K wiper resistor to at least 25K min for better isolation. The output pots should be lower in value with min 1/4 to 1/2 value wiper lead trailing resistors. Two 1k output pots with added 250 or 500 ohm wiper lead resistors would be an improved circuit. The lm-386 will be more stable into the lower impedance load. The power supply lead should be decoupled with a series 10 ohm resistor. While you're in the mood, at least one added 220pf disc cap would keep stray rf under control. If you have problems with RF in the circuit, you can use small value disc caps in the non gain portions of the circuit to tame minor problems. > 3. I would like to look at using a IC switch > on the above 6 inputs, that allow the inputs > to be switched when required? Believe the IC > would be a 4040, but I would have to double > check. I know some repeater controllers use > this chip to control the audio paths. Depends if you want to gate a single audio source with a switch/multiplex chip or gate each source as desired. The 4053 is popular, grounding the alternate pole increases isolation. You can probably find an original ACC RC-85 controller diagram to use as a guide. Another gated audio chip choice is the 4066/4016 > I will attempt to draw a circuit of my > thoughts if this would help, but I > think the above may explain enough. > Regards > Kevin, ZL1KFM cheers Kevin, skipp www.radiowrench.com/sonic Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
