rbolijn
Newbie level 2
Hi everyone,
I'm new on this forum, and i'm hoping for your help!
I'm currently working on the design of an ultrasonic sensor. I'm using a 40kHz ultrasonic transceiver (both receive and transmit). The transceiver is driven by a transformer with 1:10 turn ratio. Parallel to the transducer i want to implement a variable resistor with high resistance at the time of the ultrasonic burst (50kohm-100kohm) and low resistance just after the burst (500ohm - 1kohm) for probably around 0,1ms. Then the resistance should be high again in order for the received echo not to be damped.
I red quite a lot already about jfets as voltage controlled resistors. Still i'm finding it hard to find the right one. The drain will be grounded, the source will be an ac-signal (+30 volt to -30 volts) and the gate will be max 3,3 volts.
Do you guys have any ideas on which jfet to use?
I'm new on this forum, and i'm hoping for your help!
I'm currently working on the design of an ultrasonic sensor. I'm using a 40kHz ultrasonic transceiver (both receive and transmit). The transceiver is driven by a transformer with 1:10 turn ratio. Parallel to the transducer i want to implement a variable resistor with high resistance at the time of the ultrasonic burst (50kohm-100kohm) and low resistance just after the burst (500ohm - 1kohm) for probably around 0,1ms. Then the resistance should be high again in order for the received echo not to be damped.
I red quite a lot already about jfets as voltage controlled resistors. Still i'm finding it hard to find the right one. The drain will be grounded, the source will be an ac-signal (+30 volt to -30 volts) and the gate will be max 3,3 volts.
Do you guys have any ideas on which jfet to use?