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Converting voltage to resistance – My input is a 0-5 V signal. The voltage in this terminals is between this range: 15 to -15 V. The aim is to attenuate it with the resistor. Read more
Modernizing two audio filters – Here are two audio filters for receivers. I would like to test them but I want to make them using NPN transistors instead. Is it enough to replace the PNP transistors with NPN and put a positive VCC where a negative exists now? Also any guess of their operation principles? Read more
Mains isolation with specialty transformer – I desire to measure mains voltage of 230V AC 50Hz as a means of protecting a pump from running at certain low voltages. I have been canvassing for a suitable way I can go about it in a way that I have galvanic isolation of the mains from my control system at a very low cost. I stumbled into this transformer by TDK Corporation: ATB322524-0110 and it is very cheap. I intend to reduce the mains voltage by resistor voltage divider network. Do you think this transformer suitable for the purpose? Do you think I should use some other isolation component instead? Read more
Remove phase lag of voltage transformer – I am working on an energy meter design which uses a 1:1 transformer for voltage measurement and current transformer for current measurement. While experimenting, I found the voltage transformer’s output signal lags by approximately 30 degrees with the input signal. Is there a way to remove this phase lag? Read more
Simple amplifier design – What do you think about this amplifier? Yes, I know the power step, class AB, has no polarization (but with Multisim an error occurs if I place the polarization diodes). Read more
Optocoupler: CTR and REL_CTR – I am studying optocouplers for first-time use. I understand the CTR parameter but not the relative CTR.
1. What is relative CTR and what is it used for?
2. Is there a relationship between CTR and Relative CTR? If there is, what is the relationship?
3. I am designing a simple on/off control system with a process switch as a sensor. I desire a cost-effective optocoupler for the isolation and I chose the Vishay’s TCMT4106. Is this optocoupler appropriate for this requirement? Read more
150V to 5v logic converter – I have a 150V signal coming from a capacitor discharge ignition system that goes into a coil to produce high-voltage that goes toward the spark plug (i.e. CDI). I want to obtain and analyze the timing of the signal from in between the capacitor and the coil and record it on a logic probe. I need some device that will convert the 150V pulse to between 5V-3.3V. the device needs to be fast. Can anyone suggest a device that would be suitable for this application? Read more
Analog output or 4- 20 mA from SCADA – I have an actuator at 240 V that can take an analog output of 4-20 mA signal. I want to change the voltage difference from 2V to 1V. What value in resistance should I change? Read more
Simple, discrete, audio compressor circuit needed – I need discrete components circuit for an audio compressor, or automatic audio level control, or audio limiter for my receiver.
I want to bring the low-level audio signals and the high-level audio signals at the same audio level. I am trying not to attenuate the audio output of it much, so the circuit must have close to unity gain. I have tried the circuit below but it did not have any effect on my receiver; it only attenuated the audio quite a lot. Any ideas? Read more
Need changes in this battery monitor circuit – The battery monitor circuit shown in the diagram works with a voltage difference of 2V. At 27 V, all the LEDs glows. At 25 V, LED 1 gets off . At 23 V LED 2 gets off. Only LED 1 remains off. I want to change the voltage difference from 2V to 1V. What value in resistance should I change? Read more