3 transistor fm transmitter with coil on circuit board

Q: Can I use an 'AC adopter' for 12 volts?Ī: You can, but sometimes it may cause hum nose. This means to reduce the power voltage to the first section. where to connect aerial and if any parts need adding or changing?Ī: When you have too hot temperature at 2SC2538 (when the adjustment of the final coil is complete, it will not become hot, anyway), you may exchange 50 ohm (I suggested to change before) at 2SC1907's C for 100 ohm. Do I need to adjust the loading on the 2053, so it passes less current? Do you have any ideas how I may get the best output - i.e. I assume this might damage it if I let it get too hot. Q: When I tested the completed circuit, the 2SC2053 gets very hot after a minute or two. The reason may be that the matching is not correct or the coil is not appropriate. Q: What is the function of the 3.5 turn coil above the 2053? It does not seem to have much effect on the quality of the sound on my receiver when I move the core.Ī: This is for adjusting the matching with the original signal. The second and final coil must be adjusted to maximize the strength of the power meter. (3) Before connecting the antenna to the final output (where 100pF is connected), you must adjust the final 3.5 coil. Although it is not so easy to build a frequency counter by yourself, it would be easier to build a power meter. And prepare a power meter and a frequency counter. Please check a vacant frequency in your FM dial of your radio receiver. (2) You must decide the frequency you want to transmit. (1) Don't supply the power (12 volts DC) before connecting the appropriate antenna (even if it is a simple coax cable antenna that I made instantly). Q: Can you make sure of the position for the transistors to be soldered.ĢSC1907 E - to 33pF, 33pF, 10pF, 2-3 micro H. Q: When I build the final stage, is the 1 microH choke above the 1970 meant to be of a bigger type than the small resistor-like ones that I'm using in the rest of the circuit?Ī: the 1970 needs much ampere than the 2538 or 1907, so that it must be bigger. There are quite a lot of replacements (MV209, MMV元102) and the exterior is different. I used '1SV101' the capacity is 10-25 pF by the voltage change. Q: What type of varicap diode is required?Ī: 'varicap diode' is called as 'variable capacitance diode', 'voltage controlled diode', or 'tuning diode' too. A: Higher frequency characteristics will be preferable. Solder the wires and the leads of the register. Give the wire 20-25 turns around the register. Prepare 4.7K ohm register (1/8 - 1/4 watt) and 0.2-0.5 mm coated wire. Different from the 'simplest' model, unstable conditions of every section can cause problem of transmission and interference.Ī: Yes it is possible.

If you want to use air coil, you must use a bit thcker wire like 1.0 mm and protect them from trembling that leads unstable frequency. Q: Do the coils have an air or ferrite core?Ī: Ferrite core. >See 'How to supply the power' and the Diagram. Stabilizer for 12 vols (semiconductor) and the necessary capacitor (1000MF Electrolytic/25volts) But it is a compromise, though.Ĭoax Cable RG-62-u or RG-213 ->See 'How to make a simple antenna?' In case you can't obtain this material, you can use 'porous circuit board'. Please note that for this work, you must have a frequency counter by all means.ġ Variable Capacitor (Vari-cap) Prepare a 5.0 mm diameter cylinderical material and enameled/polyurethane wire of 0.8-1.0 mm diameter. When you make coils by yourself->Diagramġ 8.5 Turns Molded Coil (5mm diameter bobbin)(inductance=ca.0.6-0.7MH)Ģ 3.5-4.5 Turns Molded Coil (5mm diameter bobbin)(inductance=ca.0.3MH)

3 transistor fm transmitter with coil on circuit board