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  1. CDRIVE

    Activate transistor with piezo disc

    Hello Drottson, Please forgive the hostility evident in my last post. I posted that soon after arriving home after a 30 mile cycle through a thunderstorm, hauling something that was not solidly affixed (bad prep) to my bike. Two miles from my house I got into verbal warfare with a motorasst...
  2. CDRIVE

    Activate transistor with piezo disc

    How in the world did you come up with THAT circuit from the information that I've posted regarding typical 555 monostable circuit? Also, if I searched back through every single post in this thread will I find any mention of R1 (1MΩ)? While you're pondering those questions I'll see if I can find...
  3. CDRIVE

    Activate transistor with piezo disc

    The formula for monostable operation is T = 1.1*R*C but there are copious amounts of free online calculators like this one 555 Monostable Calcutator and this one 555 Monostable / Astable Calculator. Since the Piezo output voltage can be easily loaded I believe the value of the Trigger pullup...
  4. CDRIVE

    A means of closing a JFET switch with a postive voltage?

    Are you referring to supply rail decoupling caps, which are synonymous? Chris
  5. CDRIVE

    Problem with picaxe 14m2

    When you get back I'll explain the "Hard Reset" procedure which, it's my bet, you're in need of. Chris
  6. CDRIVE

    Activate transistor with piezo disc

    Drottson, here's an image of the hookup I described in post 50 but with the 0.1μF coupling cap omitted. I don't recommend omitting it though as I've read quite a few piezo datasheets that make note of blocking DC voltages from the piezo. These datasheets state that prolonged DC voltages across...
  7. CDRIVE

    Activate transistor with piezo disc

    For those following this thread and have not worked with Piezo-Electric sources before (like me) and are curious how high the (unloaded) output voltage can swing, I submit these links. Piezo-Electric Output Scope Shots Here's a TI PDF that addresses Piezo-Electric Amplifiers So far from what...
  8. CDRIVE

    Activate transistor with piezo disc

    Yes, like that but the circuit is not showing the viewer how to interface the Trigger pin. The trigger pin has a very high input impedance. Because of this you may be able to loose the transistor completely and drive this pin directly from the Piezo. Try the following: (1) Connect a 100KΩ...
  9. CDRIVE

    Activate transistor with piezo disc

    Would anyone like to draw Drottson a 555 monostable pulse stretcher? Chris
  10. CDRIVE

    Activate transistor with piezo disc

    Just to not be a total pr!ck I thought you may be interested in these links. Wiki Piezo Switch Discover Circuits Piezo Switch Chris
  11. CDRIVE

    Activate transistor with piezo disc

    This statement leaves me speechless. You don't see the value of referring to a component as R2 as opposed to "The 10K resistor connected to Emitter of the 2N3904"??? :rolleyes: Suppose there were more than one 10K resistors that were connected to other 2N3904's? It's lame to even question this...
  12. CDRIVE

    Activate transistor with piezo disc

    You appear to be ignoring my requests for component name/number identifiers. Perhaps if I BEG? On another note, you launched this thread typical of sooooo many other nubes that provide vital information analogous to feeding a patient through a Drip Tube! It would have made more sense to have...
  13. CDRIVE

    Activate transistor with piezo disc

    Perhaps this may work. Chris
  14. CDRIVE

    Problem with picaxe 14m2

    Dev, we haven't heard from you. What's the status of this topic? I ask because I encountered the same issue with a 08M2 but it was code related. Beware of the "Disconnect" command! Executing a "Hard Reset" fixed it. Chris
  15. CDRIVE

    LEDs Parallel or Series

    If I wasn't involved with my own hair pulling project I'd draw it for you. As I stated earlier it's difficult to discuss your circuit when it doesn't contain component Name/Number designations. It's a royal peta to have to describe a component as "The 555 located on the top left of your...
  16. CDRIVE

    Total beginner... so I don't know if what I want to do is easy or hard!

    Yes, a Double Pole Double Throw will give you Forward - Reverse. Chris
  17. CDRIVE

    Simulate a variable capacitor

    I read that as variable caps in the .022uF / .047uF range were available. Chris
  18. CDRIVE

    Activate transistor with piezo disc

    The way D2 is connected would not protect the transistor when the Piezo voltage swings negative. Odds are the Diode went West along with the transistor. D2 should be connected as I previously described. Chris
  19. CDRIVE

    LEDs Parallel or Series

    It would be good practice to label (component number) all components on your schematic. This way we can refer to them IE .. Rn, Un, Cn, Sn, etc. Anyway I would rethink that circuit. Bringing the GND pin of the 555 high would not be considered orthodox and will probably drive the FET nuts...
  20. CDRIVE

    Simulate a variable capacitor

    I see by this link that my assumption of an RC filter was in error since these appear to be bandpass filters that will include "L". I thought we were talking about LPF/HPF RC networks. :oops: Chris
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