60V Pulse at 1.2 MHz

I am very new to Arduino, but I have built a TTL trigger which sends a 4.3V, 2000 ms pulse using a nano board (following GitHub - nakulbende/TTL_Trigger: Make a TTL trigger using Arduino. This version outputs to a BNC terminal commonly used in scientific instruments. The sketch also includes an option to define duration for which the TTL trigger will be on HIGH.). It turns out that this amount of power is insufficient for my application.

I am attempting to send a series of pulses to a piezo-electric crystal (and an LED for the same duration). The piezo-electric crystal has to be cycled or gated. So I need to oscillate excitation pulses at 1.2 MHz (i.e. 400 nsecs on / 400 nsecs off). What I would like to happen is when I push a button (linked to the reset pin), it lights an LED for ~5 seconds from pin 13 while also pulsing 60v at 1.2 MHz for the same duration from another pin.

My assumption is that I can do this using a T1P120 transistor using analogwrite. Does anyone have any advice or suggestions? I would greatly appreciate any feedback.

What you are trying to do might be a little clearer is you provided a link to a data sheet for your piezo. You discuss needing power to do this thing but only describe signals, pulses and square waves from an analog output pin.

Paul

Here are the specs:


  • Resonant Frequency: 1.2 MHz
  • Material: PZT-5H
  • Shape: cylinder (length 0.05 inches, width 0.05 inches, wall thickness 0.01 inches)
  • Capacitance: 420-550 pF
  • Bandwidth: around 200KHz.
  • Maximum Input Voltage: around 1kV (limiting factor is wire insulation and our sonomicrometer board circuitry)
  • Power Consumption/Efficiency: we use a very small duty cycle (about 0.009%)

Operating Specifications:

  1. Bandwidth: Our 2 mm crystals operate at about 2 mHz. Due to the nature of the crystals the bandwidth is very narrow at about 200 kHz.
  2. Load, Capacitive or Inductive: The crystals act as a capacitive load when out of the bandwidth of operation. Then within the bandwidth they operate as an inductive load. There different electrical models for the operation of the crystals, however the most widely accepted is the Mason, and KLM models.
  3. Nominal Input Voltage: We pulse the crystals with a short duration pulse with a peak to peak voltage of about 100v.
  4. Maximum Input Voltage: Maximum input voltage is near 1kV. The limiting factor is more likely the wire insulation and the PC board circuitry, rather than the actual crystals.
  5. Power Consumption and Efficiency: We use a very small duty cycle ( about 0.009%)
  6. Preferable Input Waveform: Due to the narrow bandwidth of the crystal they are very accepting to the type of pulse that they receive. However, for optimal performance, you want to keep the fundamental frequency of the excitation pulse near operational frequency of the crystal.

The typical use for these crystals is via a 60 volt pulse charge when we ping them. This excitation pulse is delivered as square-wave which lasts anywhere from 125 to 500 nsec (the user can select this pulse duration in the acquisition software interface of our sonomicrometer).

When the crystals are operating is resonant mode, they behave as inductors. When the crystals are operating in non-resonant mode, they behave as capacitors.


I will be using this crystal in a non-standard way to create an artifact in the ultrasound video I will be capturing (it will show up as ‘sparkle’) such that I can synchronize the video capture with a motion capture system by linking the first frame with noise/artifact with the first frame that the LED is lit in the motion capture system.

A 5:1 pulse transformer might be useful for driving this piezo element - using 12V primary circuit you get 60V without needed any higher voltage supply.

For that frequency of operation a MOSFET will be needed, using a gate driver chip. A TIP120 will not work at that frequency as its a darlington.

If driving directly at 60V again a MOSFET with a gate driver chip will work, the driver chip both giving the switching speed needed and protecting the MOSFET gate from dV/dt issues.

From the description it seems the crystal is designed to be driven very shortly - maybe even single pulse if I understand it correctly. Are you sure it will survive being driven for 5 sec with 1.2MHz and 60V?

Smajdalf:
From the description it seems the crystal is designed to be driven very shortly - maybe even single pulse if I understand it correctly. Are you sure it will survive being driven for 5 sec with 1.2MHz and 60V?

They quote 0.009% duty cycle of operation - this implies it will be destroyed at 100% duty cycle!