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Measuring telephone line voltage with an MCU – I want to measure telephone line voltage without affecting the line with an MCU. The MCU will have an independent power supply (obviously) therefore isolation is required. I was thinking about using optocouplers. Read more
How to design an opamp circuit for pH Sensor – The pH sensor gives 420 mV for 7pH and -420 mV for 14 pH. I need to design an opamp circuit using 741 or LM358. The output of the amplifier will be input to ADC of PIC for measuring the pH. Read more
What type of battery is this? – Please refer to figure above. I think it’s a battery. Does anyone know what type of battery it is? Read more
Charger circuit issues – I put this circuit together that charges the 3.7V Lipo battery and also produces 3.3v at the output. An LED indicates the charging status. I am getting 3.3v output but the LED is not lighting up and the status pin is showing zero volts. Is the charging part of the circuit correct ? Read more
Amplifier, dead transistors, over-bias or oscillation – I built this and it worked only a few seconds when the fuse in the primary blew. Then I found out that the output transistors are dead -> 2x TESLA KD3055. Do I need to increase R5 or this is an oscillation issue? Read more
Hi-resolution audio circuit – How do we implement hi-res audio function in our circuit? Do we need special ICs to do that? Read more
Buck converter simulation not working – Can someone help me simulate a buck converter on proteus with a switching frequency 2kHz? Read more
Simulating a transistor’s avalanche in a pulse generator circuit – I’m making a board to produce a sub-nanosecond pulse using an avalanche transistor. The second Fig is the waveform I tested using a 4GHZ bandwidth oscilloscope. But when I want to produce a more narrow pulse, I don’t know which parameter should be adjusted. I had simulated this circuit with ADS and it works well. But I doubt its result because what I used transistor module in this circuit doesn’t have parameters about avalanche. How can I find a transistor simulation model that contain avalanche parameter and the success simulate avalanche breakdown to produce a pulse? Read more
