I recently made a transmitter and shared my customer experience. with enthusiasts to create a radio transmitter, use basic circuit diagrams and parts to build, and finally build a radio transmitter. In fact, many netizens have successfully created their own radio transmitters using this article. If you want to make a radio transmitter yourself, please read this article carefully, hope it helps you.
1.75" x 2.5" (45mm x 68mm) and has a range of approximately 30 meters. The documentation with the circuit says the frequency range is 100-108 MHz, but I found it closer to 85-100 MHz.
The circuit is (of course) mono only, and accepts audio input from either a microphone or other source. The input impedance is 1Mohm. The input sensitivity is 5mV and the max input signal is 10mV. The transmitted signal can be picked up on an FM radio. The circuit can be used for short-range transmission, for example. for wireless microphones.
The actual circuit comes from a 'kit', available from Veleman Electronics (US distributor is Tapto Corp, PO Box 1339, CLAREMONT NH-03743 USA. UK distributor is High-Q Electronics, 382 Edgware Road, London, W2 1EB). The kit number is K1771. He is a very good transmitter.
I bought the kit, and walked around, which worked great. I wanted two transmitters, so I made my own "copy" PCB and built the circuit, and in fact my home-made version seems to work better than the original! So there's no need to buy the kit really, as it's quite a simple circuit, and is the best "homemade" transmitter I've seen.
CIRCUIT.GIF is the circuit diagram.
PCBPLAN.GIF shows the assembly diagram from the top (components shown). PCBPLAN.GIF is an accurate layout, digitized from the instruction sheet. I used * to mark a corner for reference.
TRACKS.GIF shows the track trace on the solder side of the board. It's not a very precise route. This is because I don't really have a plan of the lane layout. To get TRACKS.GIF, I put some OHP film on the bottom of the PCB, and traced the tracks with an OHP pen. I then swept this in. I marked the holes for the component legs (approx) with white spots.
CONSTRUCTION:
Start by scaling PCBPLAN.GIF and TRACKS.GIF by the same amount so that they measure approximately the correct size (1.75" x 2.5") when printed.
So make your PCB. As mentioned before, PCBPLAN.GIF gives the precise positioning of the holes, while TRACKS.GIF gives the positions only approximately. So use PCBPLAN when drilling holes in your circuit board. Then draw over the tracks, using TRACKS.GIF as a guide. The important thing is to make sure you draw the "printed coil" correctly on the board - the lines are there for a reason!
Pieces:
D1 varicap diode (eg BB119)
D2 1N4148
R1 100K
R2 220K
R3 22R
R4 1K trimmer
R5 1K
R6 56K
R7 1M
R8 1K2
C1 5pF ceramic
C2 6pF ceramic
C3 15pF ceramic
C4 trimmer cap
C5 15pF ceramic
C6 1nF ceramic
C7 100uF electrolytic
C8 4.7uF electrolytic
C9 100pF ceramic
T1 BF244A or FET BF245A
T2 FET 2N3819
T3 BC307/8/9 or BC557/8/9 PNP
Keep in mind that, in addition to the components, there is a jumper that needs to be fitted (marked with a dotted line in PCBPLAN.GIF).
The power supply to be used is 9-14V DC, one of the small 9V rectangular batteries is fine. Connect it to the + and - points on the PCB. The sound input goes to the points marked "MIKE". The antenna should be connected to the point marked "ANT". The transmitter output impedance is 50 ohms. You can make your own fancy antenna if you like, but I've found a foot or two of wire is fine.
Good luck with the transmitter. If you have any improvements to the circuit, I would be happy to hear from you. - Dan Evans.
Conclusion:
looking at the end of this article, I believe you know how to build a radio transmitter. If you have any questions or comments, please do not hesitate to contact me.
I recently made a transmitter and shared my customer experience. with enthusiasts to create a radio transmitter, use basic circuit diagrams and parts to build, and finally build a radio transmitter. In fact, many netizens have successfully created their own radio transmitters using this article. If you want to make a radio transmitter yourself, please read this article carefully, hope it helps you.
1.75" x 2.5" (45mm x 68mm) and has a range of approximately 30 meters. The documentation with the circuit says the frequency range is 100-108 MHz, but I found it closer to 85-100 MHz.
The circuit is (of course) mono only, and accepts audio input from either a microphone or other source. The input impedance is 1Mohm. The input sensitivity is 5mV and the max input signal is 10mV. The transmitted signal can be picked up on an FM radio. The circuit can be used for short-range transmission, for example. for wireless microphones.
The actual circuit comes from a 'kit', available from Veleman Electronics (US distributor is Tapto Corp, PO Box 1339, CLAREMONT NH-03743 USA. UK distributor is High-Q Electronics, 382 Edgware Road, London, W2 1EB). The kit number is K1771. He is a very good transmitter.
I bought the kit, and walked around, which worked great. I wanted two transmitters, so I made my own "copy" PCB and built the circuit, and in fact my home-made version seems to work better than the original! So there's no need to buy the kit really, as it's quite a simple circuit, and is the best "homemade" transmitter I've seen.
CIRCUIT.GIF is the circuit diagram.
PCBPLAN.GIF shows the assembly diagram from the top (components shown). PCBPLAN.GIF is an accurate layout, digitized from the instruction sheet. I used * to mark a corner for reference.
TRACKS.GIF shows the track trace on the solder side of the board. It's not a very precise route. This is because I don't really have a plan of the lane layout. To get TRACKS.GIF, I put some OHP film on the bottom of the PCB, and traced the tracks with an OHP pen. I then swept this in. I marked the holes for the component legs (approx) with white spots.
CONSTRUCTION:
Start by scaling PCBPLAN.GIF and TRACKS.GIF by the same amount so that they measure approximately the correct size (1.75" x 2.5") when printed.
So make your PCB. As mentioned before, PCBPLAN.GIF gives the precise positioning of the holes, while TRACKS.GIF gives the positions only approximately. So use PCBPLAN when drilling holes in your circuit board. Then draw over the tracks, using TRACKS.GIF as a guide. The important thing is to make sure you draw the "printed coil" correctly on the board - the lines are there for a reason!
Pieces:
D1 varicap diode (eg BB119)
D2 1N4148
R1 100K
R2 220K
R3 22R
R4 1K trimmer
R5 1K
R6 56K
R7 1M
R8 1K2
C1 5pF ceramic
C2 6pF ceramic
C3 15pF ceramic
C4 trimmer cap
C5 15pF ceramic
C6 1nF ceramic
C7 100uF electrolytic
C8 4.7uF electrolytic
C9 100pF ceramic
T1 BF244A or FET BF245A
T2 FET 2N3819
T3 BC307/8/9 or BC557/8/9 PNP
Keep in mind that, in addition to the components, there is a jumper that needs to be fitted (marked with a dotted line in PCBPLAN.GIF).
The power supply to be used is 9-14V DC, one of the small 9V rectangular batteries is fine. Connect it to the + and - points on the PCB. The sound input goes to the points marked "MIKE". The antenna should be connected to the point marked "ANT". The transmitter output impedance is 50 ohms. You can make your own fancy antenna if you like, but I've found a foot or two of wire is fine.
Good luck with the transmitter. If you have any improvements to the circuit, I would be happy to hear from you. - Dan Evans.
Conclusion:
looking at the end of this article, I believe you know how to build a radio transmitter. If you have any questions or comments, please do not hesitate to contact me.
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