Willen
Well-Known Member
Hi,
Searching about 3 years I got very nice solution by Dick Cappels (member here too) and going to make this stereo encoder for FM transmitter. He used simple colpitts oscillator which has 1nF base capacitor to ground. Some people worry about this capacitor because upper frequency of 53KHz MPX might be cut down. Mr. Dick played with it but he got nice channel separation. Increasing the cap value, he got R is being decreased.
So I am feeling to use another type of oscillator (maybe Hartly?) which will accept whole 53KHz MPX without any error and which will modulate FM nicely without noises. I simulated a circuit too- what about it? Any improvement? My another main problem is 'Modulation Factor' because I cannot see effectiveness of MPX modulation to carrier. 'Carrier factor' is fine in simulation.
(I have collected four another circuits too, will attached here but as a #2 post because using cell phone I cannot upload two photos at the same time.)
Searching about 3 years I got very nice solution by Dick Cappels (member here too) and going to make this stereo encoder for FM transmitter. He used simple colpitts oscillator which has 1nF base capacitor to ground. Some people worry about this capacitor because upper frequency of 53KHz MPX might be cut down. Mr. Dick played with it but he got nice channel separation. Increasing the cap value, he got R is being decreased.
So I am feeling to use another type of oscillator (maybe Hartly?) which will accept whole 53KHz MPX without any error and which will modulate FM nicely without noises. I simulated a circuit too- what about it? Any improvement? My another main problem is 'Modulation Factor' because I cannot see effectiveness of MPX modulation to carrier. 'Carrier factor' is fine in simulation.
(I have collected four another circuits too, will attached here but as a #2 post because using cell phone I cannot upload two photos at the same time.)
Attachments
Last edited: