The following schematic shows the design of an VHF/UHF TV Modulator Circuit Diagram and Electronic Components. This circuit processes video signals to enable them to be fed straight into the TV set’s aerial input. A TV modulator is a very small transmitter/oscillator that generates a frequency somewhere in the VHF or UHF region.
The TV modulator is made up of two parts, namely a modulatable crystal oscillator and a harmonics generator. The oscillator operates at a frequency of 27 MHz. The harmonics generator converts the oscillator signal into a sort of frequency spectrum containing all the multiples of 27 MHz up to about 1800 MHz. The TV modulator’s output signal is made up of a large number of little peaks, each of which is a complete transmitter signal.
VHF/UHF TV Modulator Parts/Components:
Resistors:
R1, R2 = 4k7
R3, R4 = 56ohm
P1 = 100 ohm preset
P2 = 500 ohm preset
Capacitors:
C1 = 4mf7/16 V
C2= 10p
C3 = 220p
C4 = 47p
C5 = 47n, ceramic
C6 = 100n*
C7 = 330n*
Inductors:
L1, L2 = 3.5 turns of 0.2 mm (SWG 35 or 36) CuL on a ferrite bead of about 3.5 x 3.5 mm
L3 = 1 microH
L4 = 1 turn of 0.8. . .1 mm (SWG 19…21) CuL, air wound with a diameter of 8 mm
Semiconductors:
D1, D2 = 1N6263 (Ambit/Cirkit)
D3 = lN4148
T1 = BFR91 (Ambit/Cirkit)
IC1 = 7805*
Miscellaneous:
X1 = crystal, 27 MHzd(3rd overtone) or other 3rd overtone crystal between 25 and 30 MHz
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1 comment for this entry ↓
1 sagaryelavdekar // Feb 25, 2012 at 8:32 pm
i wanted to made this circuit for study the uhf oscillator,is it give the correct frequency.
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