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R_Gol
Joined: Oct 17, 2019 Posts: 34 Location: World
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Posted: Thu Jan 16, 2020 12:49 am Post subject:
simple FSR schematics ? |
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Hi,
I've got two of the FSR 402 Round Force Sensing Resistor( Adafruit)
and I could not find any simple schematic in order to build a cv generator with change of voltage when pressing (Style of the pressure Points by Make Noise)
is anyone could point me to a schematic making the above ?
Any help will be appreciated!
Many Thanks |
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JovianPyx
Joined: Nov 20, 2007 Posts: 1988 Location: West Red Spot, Jupiter
Audio files: 224
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Posted: Thu Jan 16, 2020 10:04 am Post subject:
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Since it's a resistor, there can be several ways to get an electrical signal from it. The datasheet will tell you the maximum current you can draw through it. An extremely simple way to get a signal is to form a voltage divider with it. Pick an upper resistor value that limits current to no more than the maximum allowed at your power supply voltage and connect one end to V+. Connect the other end to one end of the force sensor and ground the other end of the sensor. A voltage will be present at the connection of the R you picked and the force sensor. The voltage will change with pressure on the sensor.
The voltage will not be linear with respect to pressure. There are other ways to use the sensor to get a linearized signal. However, nonlinearity may also be inherent in the sensor design, so it may be tricky to get a truly linear voltage - if that's what you need. _________________ FPGA, dsPIC and Fatman Synth Stuff
Time flies like a banana. Fruit flies when you're having fun. BTW, Do these genes make my ass look fat? corruptio optimi pessima
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R_Gol
Joined: Oct 17, 2019 Posts: 34 Location: World
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Posted: Thu Jan 16, 2020 10:56 am Post subject:
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JovianPyx wrote: | Since it's a resistor, there can be several ways to get an electrical signal from it. The datasheet will tell you the maximum current you can draw through it. An extremely simple way to get a signal is to form a voltage divider with it. Pick an upper resistor value that limits current to no more than the maximum allowed at your power supply voltage and connect one end to V+. Connect the other end to one end of the force sensor and ground the other end of the sensor. A voltage will be present at the connection of the R you picked and the force sensor. The voltage will change with pressure on the sensor.
The voltage will not be linear with respect to pressure. There are other ways to use the sensor to get a linearized signal. However, nonlinearity may also be inherent in the sensor design, so it may be tricky to get a truly linear voltage - if that's what you need. |
Thank you! I tried what you say and its working!
I saw in the datasheet of the FSR this schematic(https://imgur.com/a/JlFEACF) that using an op-amp( LM358 or LM324 ) with the resistor.
why to do so and what is the difference from the method you mention?
Thanks |
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JovianPyx
Joined: Nov 20, 2007 Posts: 1988 Location: West Red Spot, Jupiter
Audio files: 224
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Posted: Thu Jan 16, 2020 12:42 pm Post subject:
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That is a method of linearization. The signal out depends on the current in which is directly controlled by the FSR. That circuit is better than the simple voltage divider.
Additionally, the opamp buffers the signal so it is strong enough to drive whatever you need. _________________ FPGA, dsPIC and Fatman Synth Stuff
Time flies like a banana. Fruit flies when you're having fun. BTW, Do these genes make my ass look fat? corruptio optimi pessima
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R_Gol
Joined: Oct 17, 2019 Posts: 34 Location: World
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Posted: Thu Jan 16, 2020 12:43 pm Post subject:
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JovianPyx wrote: | That is a method of linearization. The signal out depends on the current in which is directly controlled by the FSR. That circuit is better than the simple voltage divider.
Additionally, the opamp buffers the signal so it is strong enough to drive whatever you need. |
Great thanks! |
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The Peasant
Joined: Nov 13, 2009 Posts: 99 Location: Sunny Alberta
Audio files: 1
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