Split = branch a wire as you have done, only be sure that the possible mic supply voltage DC from "the device" doesn't get into your own circuit. If I needed it, I would build it - one battery, one dual audio amp IC, one potentiometer, few caps and few resistors and proper case+connectors, maybe also a battery switch if it cannot be a part of a connector. I bet someone has already invented this device and it's for sale somewhere. The mixer should be able to produce the needed output power for your headphones and split the mic signal to where it's actually used. The stereo input should be able to handle headphone signal level, which is pretty much more than normal audio device line signals. The mixer should be able to supply your mic with the common 1.3VDC, if the mic is of the usual electret type. Obviously you cannot feed the mic signal back with the available settings in "the device", so you need a mixer - one which accepts your mic signal as one mono input and the headphone signals as one stereo input. To answer previous question on mic voltages (headset connected directly to device): When switched off, preamp output goes to zero, and M+ signal goes to normal.Īny suggestions for retaining signal quality at M+ when circuit is powered ON? Cursor shows where circuit is switched OFF. Mic is picking up a loud tone from a tone generator. Connected to oscilloscope to demonstrate. When the circuit is not powered (3v off) the output to the device returns to normal (and nothing can be heard in headset as the speaker amps have no power, of course). When the circuit is powered (3V on) the mic output to headset is loud and clear, but the mic output to the device is very muffled and quiet. Regarding your final statement on ground wiring, are you suggesting arranging the ground wires in a manner such as the below diagram: Since the amount of gain on preamp is unknown, would it make sense to add a potentiometer? If so, what min max values would you suggest? Is there any risk of damaging the headset/device? Is it even feasible to run this off 2AA batteries? There is also no need for master volume control, but I’m worried I won’t be able to select the proper resistor value.Īre the resistors/pots/capacitors sizes critical? If so, any suggestions? The speakers on the headset are 32ohm and the microphone is 2200 ohm.Ĭould the number of amplifiers be reduced?Ĭould the number of pots be reduced? Note that there would probably be 3 off 2-gang pots, as there is no need for balancing between right and left. The device would be powered by 2AA batteries. The circuit would be connected in-line between the headset and the device to which it is connected (laptop, smartphone, etc). Looking to add it to both right and left channels, with a volume adjustment. I’m looking to create a circuit to add sidetone to a headset. Will I be able to do this passively without any more amplifiers? Would anyone suggest different values for resistors/capacitors? Any other errors? I’ve added an amplifier with variable gain for the mic input to the best of my understanding, but I’m not sure about splitting/mixing the signal. So, would a standard 0.06W dual gang logarithmic pot would be adequate for this application? I’m not sure of the impedances of the device, it can be assumed to be a typical laptop computer or smartphone.Īs for power ratings, I assume the typical voltage at max volume would be less than 1V for the headphone jack on these devices.
The headset speaker impedance is 32ohms each and the microphone impedance is 2200 ohms.
#SOUND SIPHON VS LOOPBACK SERIES#
I’d like to build a passive device to loopback the mic to the headphones that would be plugged in-line between the headset and device, with a potentiometer to adjust the mic volume to headphones.Īre additional fixed resistors required? I assume it would be a good idea to put something in series with the pot for when it is turned up fully, but I’m not sure what size.100ohm? I can’t stand not being able to hear myself speak.
0 kommentar(er)
