Dual Trace CRO

The block diagram of dual trace oscilloscope which consist of following steps,

1. Electronics gun (single)

2.Separate vertical input channels ( Two)

3. Attenuators

4. pr-amplifiers

5. Electronic switch.

The two separate input signals can be applied to single electron gun with the help of electronic switching  it Produces a dual trace display .Each separate vertical input channel are uses separate attenuators and pr-amplifier stages, so the amplitude of each signal can be independently controlled. Output of the pr-amplifiers is given to the electronic switch, which passes one signal at a time into the main vertical amplifier of the oscilloscope. 
The time base-generator is similar to that of single input oscilloscope.


By using switch S2 the circuit can be triggered on either A or B
channel, waveforms, or an external signal, or on line frequency. The horizontal amplifier can be
fed from sweep generator or from channel B by switching S1. When switch S, is in channel B, its
oscilloscope operates in the X-Y mode in which channel A acts as the vertical input signal and
channel B as the horizontal input signal.




From the front panel several operating modes can be selected for display, like channel B only,
channel A only, channels B and A as two traces, and signals A + B, A - B, B ~ A or - (A + B)
as a single trace. Two types of common operating mode are there for the electronic switch,
namely,
1. Alternate mode
2. Chop mode.