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I found a diagram with an output stage supplied from ±120V here: https://www.ti.com/lit/an/snoa600b/snoa600b.pdf
For my purpose, I would need single supply - I'll keep digging.
Thanks for clarification. Are you suggesting using a high voltage transistor at the output of the opamp and use its emitter as the high voltage point for the feedback resistor?
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Thank you very much for the link and info (I had a quick look at what wenner arrays are). It's...
The test voltage is fixed and it has two steps (either 10V or 100V, depending on the measured resistance - start with 10V and if the resistance is too large to be measured, then move to 100V). The tester is used to identify if a surface (floor, work bench, chairs) is conductive, dissipative or...
I think the diagram you show is quite primitive. The antenna will influence the transmitted frequency. It would be better to use a buffer transistor at the output of the oscillator (repeater on emitter maybe). I don't think you need to change from bipolar to FET. The TV spectrum is very large...
I am trying to design a surface resistance tester. Typically such an instrument uses a high voltage between probes (100V or 10V, depending on resistance value) and it is capable of measuring values from 1 kohm to above 100 Gohm (precision is not essential, a 10% would be ok). My intention is to...
Re: beginner would like to design a circuit
Are you talking about the same project? Initially you mentioned a DC current with specific slopes and a maximum plateau value. Now you are asking about a circuitry that provides an AC current that changes with the same frequency as the voice. They are...
Re: beginner would like to design a circuit
Hi, I checked the patent. It does indeed specify the current of 10mA. Just be careful if building the circuit, don't get electrocuted :)
Re: beginner would like to design a circuit
The table which you showed us contains general information with experiments with two electrodes held firmly in hands by the subjects and for limited (short) amount of time.
The device DC Stimulator contains a lot of protection circuitry, as they say...
Re: beginner would like to design a circuit
You should be very careful if you decide to build the circuit. 50mA is a current potentially deadly for a human. Also, if you are not going to use some batteries or rechargeable batteries, there are some stringent conditions for any (medical) device...
Hi Brad,
As far as I know, if you didn't use some special resistive wire, then your measurements could be significantly affected by variations in temperature. The current going through wire can change the temperature and also the ambient temperature can affect it. For example, for copper, an...
It is just a warning for you to make sure the device you are using requires indeed a 5V supply. If you know your microcontroller works at 5V, you can disregard the message. If you are using a 3.3V device, then you need to change the power supply voltage.
Regards,
Nicolae
Hi Brad,
His circuit is ok, you can notice the value -12V in front of that power supply. If the minus were at the top, then the voltage should have been +12V.
Regards,
Nicolae
Re: beginner would like to design a circuit
Hi Brad,
He can generate voltage linear ramps by charging/discharging a capacitor using a constant current source.
Zeyad, what kind of load do you have in mind? I find quite hard to imagine the utility of such a circuit.
You could do this using a...
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