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  • Users: jimmylovesni
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  1. jimmylovesni

    creating phase delay

    thanks all
  2. jimmylovesni

    creating phase delay

    that article is a microcontroller based application, it doent really have the phase control that we looking for, that is 10-20 or 30 degrees. i still dont see that a time delay can be used to simulate a change in phase, its periodic with respect to the driving pulse yes, a microcontroller, i...
  3. jimmylovesni

    creating phase delay

    ive tried the 555 without any luck, thats the only reason i mention it. i think the timing delay and phase delay are somewhat similar if the timing delay can be triggered from a control pulse.. in that manner, it is always a fixed difference from the rising edge. Im not sure how to do this...
  4. jimmylovesni

    creating phase delay

    im trying to create a pump from three piezo disks. The have to fire just micro-millliseconds from each other to get the timing for the pumping action. I was thinking a astable 555 but was unable to get it to work. It seems to always start with the caps charged so there is no phase delay from...
  5. jimmylovesni

    creating phase delay

    anyone have an idea on how to create a phase delay which is variable. Im not talking the start 180 degree flip flops though, but more like 10-20 degrees. I know this is not that hard to do with a u controller but need to try with standard ICs. A 555 comes to mind but I havent been able to get...
  6. jimmylovesni

    biasing a mosfet or heating issue

    Hello, I am having trouble with the power consumption by a paired mosfet array chip. The should be simple circuit is attached. The mosfet array (half bridge chip – FMP26 by IXYS) is being switched at 1-2MHz and thus, a 12A pin driver (EL7158) is being used to deliverer more current to the...
  7. jimmylovesni

    measuring vibrations > 1Mhz

    how about using a ultrasound transducer in the 1Mhz range as a reciver? Maybe if the transducer is the proper size relating to the size of the vibration and wavelength? Is there a way to amplify and calibrate it for recieved ampliutide?
  8. jimmylovesni

    measuring vibrations > 1Mhz

    Hello. I need to quantify the amplitude of some vibration and waves we are experiencing. They motion is at approximately 1 to 1.5Mhz has an amplitude in the low micrometer to nanometer range. I understand that this is at the distance*frequency limit for a laser vibrometer. Other options I...
  9. jimmylovesni

    Discharging Cap causing problem in biasing of power amplifier.

    awesome, thanks!
  10. jimmylovesni

    Discharging Cap causing problem in biasing of power amplifier.

    here is the scope shot of it working.. its just a protoboard circuit with one mosfet and pin driver, but none the less, shows its fixed...
  11. jimmylovesni

    Discharging Cap causing problem in biasing of power amplifier.

    henneshoe - wow! its working!! I just wired the 1Khz to OE. Im not 100% sure about the tristate though, I do have a voltage divider of 5V, via two 10ks, on OE, is that correct? somehow clicking on "thanks" and giving you the little star somehow downplays my appreciation. Jim
  12. jimmylovesni

    Discharging Cap causing problem in biasing of power amplifier.

    I appreciate your time, but saying the RC is funny is not really helping as it is something I myself indicated as being in question. Its how to get rid of the time constant, as in 0 dealy, that was interested in. VE1Bll- thanks for your efforts again. Will try this next week.
  13. jimmylovesni

    Discharging Cap causing problem in biasing of power amplifier.

    was thinking about this a little more.. if the cap is removed, then there will be close to 50 volts on the output of the pin driver. gotta be a way to do this.
  14. jimmylovesni

    Discharging Cap causing problem in biasing of power amplifier.

    anyone else with thoughts? thanks for your input VE1BLL. Ive now debating wiring up a prototype tomorrow (this is old project and already built pcbs on it) too see if this is salvagable to answer your question, the half of the circuit (the n channel mosfet) can be connected to a negative...
  15. jimmylovesni

    Discharging Cap causing problem in biasing of power amplifier.

    there are resistors between the gates of the 7350 and pin driver.. If not, there ends up being some pretty large oscillations from impedance. they are generally pretty small in value, less than 10 ohms. the x is just for a oscillator or crystal. It can be swopped out with function generator...
  16. jimmylovesni

    Discharging Cap causing problem in biasing of power amplifier.

    I have a single oscillator which is switching numerous matched mosfets arrays (n and p) in parallel. The circuit works as it was originally intended and is able to drive an ultrasound transducer at 1MHz. This circuit is attached (US_driver.jpg). A more detailed explanation is that a...
  17. jimmylovesni

    Resonance/frequency and sounds

    im still not sure what it is at this point. there are some increases in the harmonics (overtones) that i can see via FFT in matlab.. the hydrophone through air is recording the 1MHz pulsing at 1KHz. its probably just a combination of both. thanks everyone
  18. jimmylovesni

    Resonance/frequency and sounds

    and btw.. the very first part of the signal, right where the pulse is turned on is a flextural wave, a lamb wave, its probably different from this resonance signal although Im wonder if it is helping building it up higher than normal? Is the resonance related to the piezoelectric transducer...
  19. jimmylovesni

    Resonance/frequency and sounds

    ok, I uploaded some figures of it at various frequencies. I didnt have a microphone handy so used a hydrophone. Ill try the microphone later. It seems like there is a resonance that is building up and going to a higher pulsing frequency cuts off this build up.. but this doesn't explain the...
  20. jimmylovesni

    Resonance/frequency and sounds

    I am hitting glass plate with high power ultrasound. The ultrasound pulses are 1MHtz pulsed at 1KHz. As a by product, we are getting an audible component, a high pitched ringing. As we change the pulsing rate, say over the range of 0.5KHz to 2KHz, the pitch that we hear changes. Why is...

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