Logic Probe Pulsar, when is it best to use it?

[danny davis]

When is it best to use a logic probe pulsar? to test what kind of logic IC chips?

How do you guys use a logic probe pulsar, for what use?

 

[pplus]

Imagine that you have some logic inputs connected to one output. One input is faulty and closes on the ground. Required to determine - which of them. Put the output pulse and logic probe watch status change chips connected to this output. Faulty chip status has not changed. Eureka!

 

[danny davis]

How is a logic pulsar different than a function generator? Does a logic Pulsar do anything different that it's ment for logic troubleshooting?

 

[pplus]

How is a logic pulsar different than a function generator?

The function generator has different waveforms (square, triangle, sine wave) amplitude and frequency of which can be changed. Pulse generator - the TTL / CMOS single pulse and may be square wave.

Does a logic Pulsar do anything different that it's ment for logic troubleshooting?

It is not likely, but this depends on your fantasies.

 

[chuckey]

The Hewlett Packard kit we had used a pulser and a current probe. If you had a node that was stuck you put the pulsar on it and with the current probe you could then trace where the current was going to. i.e. the short to deck, blown up output. .. .
Frank

A Pulsar is a star that is emitting light rays , hence " pulsing", like a galatic light house.

 

[danny davis]

Why is it bad to put +5 volts on the output of a TTL or CMOS chip? don't they output +5 volts HIGH signal

So I should Inject the +5 volts NOT on the output but a near by component after the output?

What you mean by the opposite voltage level? it's either zero LOW or +5 HIGH

If I apply +5 volts to a LOW signal that will cause a SHORT?

 

[pplus]

Why is it bad to put +5 volts on the output of a TTL or CMOS chip? don't they output +5 volts HIGH signal

Load component is out of range, you will damage chip.

So I should Inject the +5 volts NOT on the output but a near by component after the output?

The same thing.

What you mean by the opposite voltage level? it's either zero LOW or +5 HIGH

If ootput is LOW - HIGH and vice versa.

If I apply +5 volts to a LOW signal that will cause a SHORT?

If you apply continuously +5 volts to a LOW signal and vice versa that will cause a SHORT.

 

[danny davis]

So what continuous voltage can I apply on the output of a TTL or CMOS chip? 2 or 3 volts is that safe?

Is that why they use the logic pulsar because its not a continuous voltage and its a short duration to cause damage to the output of a TTL or CMOS chip?

What voltage can I apply to the output that is continuous DC voltage that is safe?

 

[pplus]

So what continuous voltage can I apply on the output of a TTL or CMOS chip? 2 or 3 volts is that safe?

Do not apply load, short on +5 or GND is applied zero impedance.

Is that why they use the logic pulsar because its not a continuous voltage and its a short duration to cause damage to the output of a TTL or CMOS chip?

To cause no damage to the output of a TTL or CMOS chip.

 

[danny davis]

When there is no load on a TTL or CMOS chip , what output signal is?

Is a pull up or pull down resistor a Load? what is a load? what can i use as a load on the output of a TTL or CMOS chip?

what continuous voltage can I apply on the input or output of a TTL or CMOS chip that is safe?

 

[chuckey]

You can put any voltage between 0V and Vcc on an input. You should not put any continuous voltage above about 100mV on an output. When an output is in use there is a transistor that is switched on either between the +Vcc line and the output pin or between earth and the output pin. So putting any voltage into the output pin can cause the switched on transistor to draw excessive current from your voltage source and burn out. A pulser put out a very narrow pulse so even if the transistor draws excessive current it does not have time to heat up and destroy its self.
Frank

 

[danny davis]

The Logic Pulser has a switchable pulse rate either 0.5hz or 400hz

Using a oscilloscope to view the logic pulser signal at 0.5hz is hard to view and also 400hz is also to view on my oscilloscope

 

[chuckey]

Exactly, its a narrow pulse (10 nS wide?), so it can't burn out a logic output transistor.
Frank