I found this schematic on the web, this plugs into an iPhone, an electric guitar and earphones/speakers. I see no supply, is this circuit missing anything?
Mike
See the 4th contact on the headset plug?
The circuit converts the headset electret microphone into an input for the guitar pickup. The Jfet is powered instead of the Jfet in an electret mic.
See the 4th contact on the headset plug?
The circuit converts the headset electret microphone into an input for the guitar pickup. The Jfet is powered instead of the Jfet in an electret mic.
Many headsets for phones have an electret microphone. The first sketch shows a 4-contacts plug with the 4th contact connected to the guitar circuit and it is labelled "mic".
Instead of the phone powering an electret mic then it powers this guitar circuit instead with the same very low current that it powers an electret mic.
The electret mic has the same Jfet circuit inside as this guitar circuit. No smoke.
Ok understood,
So I can connect R3 back to ground and remove C4 and 9V supply as it is in the original schematic?
Do I maintain R1 as 2.2M or 39K was good?
I have tried my circuit and I am getting some distortion. I have tried connecting to headphones and to the line input of a sound system both with the same effect.
I bought the components from a surplus store and used the closest values they had. Could that be the cause?
C1 = 20pF, the one I have is labeled 223 C5k other side:733 AKP
C2 = 100pF, the one I have is labeled 101
C3 = 470pF, the one I have is labeled 560k Z5F
Here is the schematic again:
I have tried my circuit and I am getting some distortion. I have tried connecting to headphones and to the line input of a sound system both with the same effect.
Remove R3 that is causing the output to slam into 0V with severe distortion. The circuit in the iphone has it already connected so it powers (a headset mic) or the circuit.
I bought the components from a surplus store and used the closest values they had. Could that be the cause?
C1 = 20pF, the one I have is labeled 223.
You should learn about how capacitors are marked. The third number is how many zeros are following the first two numbers and the total is how many pF. 223 is 22 followed by 3 zeros so it is 22,000pF which is 22nF.
101 is 10 followed by 1 zero so it is perfect at 100pF.
C3 = 470pF, the one I have is labeled 560k.
C3 reduces radio pickup and does not affect the audio from the circuit.
560k is 56 followed by 1 zero so it is 560pF which is almost the same as the 470pF shown. "k" means a tolerance of 10% ("j" is 5% and "m" is 20%).
Ron,
Thanks for the link, this will help a great deal.
Audioguru,
Thanks for the info, I wish i had your knowledge.
You should learn about how capacitors are marked. The third number is how many zeros are following the first two numbers and the total is how many pF. 223 is 22 followed by 3 zeros so it is 22,000pF which is 22nF.
101 is 10 followed by 1 zero so it is perfect at 100pF.