Preference of one circuit over another

Discussion in 'Homework Help' started by kiwi101, May 13, 2015.

  1. kiwi101

    Thread Starter Member

    Feb 18, 2014
    Hey guys

    In order to get a PWM signal I have chosen to use the second circuit with the Schmitt Trigger and Comparators. However the 555 timer circuit is also a valid method to obtain a PWM Signal. My question is are there any drawbacks of the 555 timer circuit so that I may explain why I chose to go with my circuit implementation. I have to make a Pugh matrix for these circuits so in terms of flexibility, cost, implementation which one do you guys think is better, and why?
    The only point I have right now is that I need a 200kHz signal and since the frequency is large the second circuit is easy to go with. Is this a valid assumption or no?

    Thanks guys.
  2. Dodgydave

    AAC Fanatic!

    Jun 22, 2012
    go with the 555 timer, its designed for timers and oscillators, less components,less to go wrong, to alter the speed change C1.
    Last edited: May 13, 2015
  3. OBW0549

    Well-Known Member

    Mar 2, 2015
    I'd say go with the 555 circuit, but make one change: use a CMOS 555 like the LMC555 or the TLC555. They take less power and they can work at higher frequencies.
  4. kiwi101

    Thread Starter Member

    Feb 18, 2014
    I already went ahead with the other configuration and after slaving for hours got my simulations to work and so I can't really go with the 555 timer, I wish I would've done that before.
    Is there any justification I can give for going with the other circuit configuration?
    I basically have to explain why I chose this over the 555 timer circuit.