Hello I am a little confused by pulse / pwm.
I noticed a lot of new function generators are arb gens these days.
They have a pulse button, which I understand is a short blip.
I believe these are used in RF to test harmonics or something. Not quite sure.
I suspect pwm would be more useful to me. eg, sensor inputs. / uC input.
The old school FG do sine/tri/square.
Not sure if square will do pwm.
Is it fixed 50/50 duty?
Finally, my understanding is the cheap dds ones on ebay, need to be paused to change parameters, eg no easy sweeps.
A pulse is just a one-time event, a sudden rise in voltage (or drop if a negative pulse) and it resumes back to "normal".
PWM (
Pulse
Width
Modulation) on the other hand describes a
characteristic of the wave. Say you have a 1KHz square wave. Each cycle of a 1KHz wave is (and by arithmetic must be) 1ms. If this square wave is 50% duty cycle,
each cycle of the wave would be 0.5ms at HI and 0.5ms at LOW. Now if you change that to 60% duty cycle, each cycle you have 0.6ms at HI and 0.4ms at LOW. In other words, you
modulated each cycle of the wave at 60% HIGH for
each wave-cycle-width. PWM describes the modulation - how much of the cycle is HI and how much LOW. You can look at the example I just described as a chain of
repeating pulses each 60% of the cycle-time. You should look at duty cycle as another characteristic of a continuous wave like
Amplitude or
Frequencies each being a
characteristic of the wave.
You can also have a 100ms
pulse of this 1KHz square wave modulated at 60% in which case you have 100 cycles, each cycle has a short pulse of 0.6ms HI and 0.4ms LOW before the next 0.6ms pluse.
A function generator generates waves with different
characteristics that you can adjust. It can generate the wave continuously, or (if pulse is available) a mere short pulse like the 100 ms pulse I described earlier.
I have a cheap Chinese DDS. It doesn't do pulse but can generate continuous Triangle, Sine, or Square saves.
PWM is adjustable for Triangle and Square. Sine is by definition 50% duty or it is NOT a Sine wave.
(If I can read your mind successfully, I think you are trying to use it for power control - I know you said sensor input/uC input, but that doesn't seem right as inputs are as the source of the input described and you don't modulate it. So perhaps you are thinking uC/sensor input to control power output.)
A function generator is not an appropriate tool to drive anything directly. It doesn't supply enough power to drive anything. However, while inappropriate, you can use it to modulate another real power source. Any square/triangle wave can be modulated. Square is probably better since it is either full-ON or OFF. 60% duty wave "turn on" 60% of the time delivering more power than a 50% "turn on". A simple square wave with adequate power and PWM will do nicely for this kind of application.
Hope this helps.
Rick