Composite-video-signal-text-adder


Posted on Feb 10, 2013

This circuit shows a simple way to add text information to a composite-video signal that might be floating at some indeterminate de level. The text generator and composite-video source must have the same sync signal. The video-input and -output signals share the same terminal. C3 couples the video signal to the output of a rectifier circuit that is based on a subvideo-speed op amp. A faster op amp would clamp on individual sync pulses rather than on the video waveform`s average value, as is desired.


Composite-video-signal-text-adder
Click here to download the full size of the above Circuit.

Rll serves as a pulldown resistor and feedback resistor RlO ensures that TP6 remains at ground level. Emitter follower Ql buffers the text signal, and R5 serves as a gain control. A simple clamp circuit, Q2, is sufficient for regulating amplitude, because the text signal contains no gray-scale levels. Q3 couples the text signal into the op-amp clamp circuit.




Leave Comment

characters left:

New Circuits

.

 


Popular Circuits

Basic-function-generator
Wideband Test Amplifier
Nokia 5800 Ringtone Buzzer Audio IHF Speaker Repair
simple common emitter amplifier
Video-Out Coupling
An Intel 8088 Maximum Mode Single Board Computer System
Push Off Push On
Fly auto disinfestation effect circuit
A typical DVD switching power supply circuit
ADT70 platinum resistance temperature measurement circuit
INA337 high-end configuration of the load current measurement shunt circuit diagram



Top