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TDA2030 active crossover circuit transistor heating up – I am trying to build the active crossover circuit of TDA2030 (Page 9 of this pdf). When I power up the circuit with 12V input power supply, the PNP transistor BD908 heats up. I am using TIP42C instead of BD908. Can anyone let me know why this is happening? Read more
Measure DC current using shunt – I want to measure the battery charging current (high-side current sensing) with a shunt and opamp (LM393). Suggestions? Read more
Using n-channel MOSFET on low side in buck converter – Can we use an n-channel MOSFET on the low side in a buck converter instead of high side for simplicity as shown in this image? In this case, we can directly drive the MOSFET from the PWM IC with minimum losses and heat. If so, then what should be the inductor value for an output of 12-14V 20A having a switching frequency of 30 kHz? Read more
ADC difference measurement in high-voltage circuit – I want to measure the voltage difference between 2 points in my circuit. That is about 30-500 mV using an ADC. Tthe problem is that the voltage of each point is about 300 VDC. Read more
Filtering frequencies from 0Hz to 20Hz – I need to implement a high-pass filter to eliminate baseline drift to my signal. The wanted frequency range is between 25Hz to 400Hz. I already implemented a low-pass filter to remove any unwanted noise above 400Hz. I need the high-pass filter to have an adjustable gain from 1 to 40 by using a potentiometer. Are there circuits/ICs to implement the high-pass filter with an order of at least 2? Read more
Current sense amplifiers supply voltage rail – I have been faced with the situation of having the to derive a low voltage supply from a rather large voltage source (<=65Vdc) and I have been looking at the available current-sense amplifiers such as LTC6102. They are apparently working with a large input voltage range. They do not require a low-voltage supply and instead seem to derive their power supply from the high-side supply (this is in a high-side current sense situation). The LTC6102 are sold in two versions, one ordinary 5-60V and one high-voltage (LTC6102HV) that can handle 5-100V. I’m curious about how that is happening. Is it a reasonable thought that such an amplifier would operate at a low voltage rail? Read more
LEM LV 25-P output drive – I have an LEM voltage transducer (LV 25-P). As the datasheet says, the maximum measuring resistor is 190 or 350Ω according to the measuring range and supply. I want to drive the output with a current to voltage opamp. I convert the LEM’s output into voltage and offset it by 2.5V. If I use the measuring resistor topology I need an 82Ω resistor. So if I use a current-to-voltage opamp can the circuit on this image work? Read more
Programmable delay line for analog signals – I have a project where I need to delay a signal with about tens of microseconds (max. 50µs) and I can only find digital delay lines or 64µs delay lines for PAL TV systems. The signal I am working with has a max amplitude of 1Vpp, with a 1.5MHz max frequency.
Can anybody help me? Read more
High voltage integrator opamp choice? I need an integrator that will handle +100v output. This is a serious problem due to the lack of high voltage opamps. It’s my understanding that integrators need to be unity gain stable. Would this opamp work? It seems to show unity gain capability under the “gain and compensation” graph but does that mean unity gain stability? Read more
Voltage-to-frequency converter – I need to make a voltage-to-frequency converter. I am using AD652. I have read the datasheet and followed a “Single Supply Operation” but I am unable to achieve output. Read more
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