Audio/Video to UHF TV Signal Converter (Modulator)

Audio/Video to UHF TV Signal Converter (Modulator) circuit

This is the circuit diagram of audio/video modulator. The circuit will convert an audio and video signal into a UHF TV signal. It’s desired to connect a video signal originating from a camera or other video source to a normal TV set. The audio and video signal is converted into a UHF TV signal so that the signal can be received through the TV antenna input.

Audio/Video to UHF TV Signal – Parts List

R1 : 47
R2 : 100
R3 : 560
R4 : 1K
R5 : 1K
R6 : 1K
R7 : 10K
R8 : 1K5
R9 : 1K5
R10 : 1K5
R11 : 2K7
R12 : 2K7
R13 : 2K7
R14 : 5K6
R15 : 270K
RV1 : 50K (47K)
RV2 : 1K
ZD1 : 11V
ZD2 : 6V2
C1 : 3pF
C2 : 3pF
C3 : 3pF
C4 : 1pF
C5 : 3pF
C6 : 10pF
C7 : 15pF
C8 : 22pF
C9 : 33pF
C10 : 56pF
C11 : 100pF
C12 : 100pF
C13 : 180pF
C14 : 470pF
C15 : 1nF
C16 : 1nF
C17 : 1nF
C18 : 1nF
C19 : 1nF
C20 : 4?7
C21 : 4?7
C22 : 10?F
C23 : 10?F
C24 : 220?F
CV1 : 5pF
T1 : BC547B
T2 : MPSH10
T3 : MPSH10
T4 : BFR90
L4 : 10,7MHz
L5 : 10?H
LD1 : Red

High Frequency Inductor Windings
This is how to make high frequency inductors for L1, L2 and L3:

  • Cut 3 lengths of the 0.6mm wire supplied to the exact length.
  • Scrape the enamel off the ends of each length of wire with a sharp knife for about 5 mm and tin the ends.
  • Make up the windings on a gimlet of 3.5mm diameter.

high frequency inductor windings
Download the application note of Audio/Video to UHF TV signal converter:

One thought on “Audio/Video to UHF TV Signal Converter (Modulator)

  1. A.J

    I have two questions
    1- what about the voltage?
    2- there is “L5 : 10?H” in the parts list but i can’t find it in the schematic!
    Thank you

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