Top analog threads on EDAboard.com – February

edalogoHigh current ferrite beads –  I have a linear regulator that is being supplied by a switching converter and as such I want to use 1 ferrite bead each on the linear regulators input and output. But that regulator is supposed to supply 10A max and while looking for beads I can find beads rated for 10A and 10,5A at the most. But I have heard that I should use a 20A bead if I want to pass 10A through it, even if that would be a little excessive 10A through a 10A bead does sound as cutting it a little too close, isn’t it? What are my options for high current ferrite beads? Read more

Choosing diode values -I need an assistance to chose the right diode values for protecting the circuit from reverse voltage and current protection. Vin 12v, max forward current /consumption of the circuit can reach 7A. Do I need to choose a 7A max forward current? Can anyone specify example models? Is it better to use a schottky diode as to fast response? Read more

Maximum feedback resistor for biasing an amplifier input -I have a question about a feedback resistor value. To bias an input of an amplifier, we can use a feedback resistor from output to input. Normally we use a high resistance, but there may be problems.
1) Amplifier input impedance
If the feedback impedance is higher than the input impedance of the amplifier, input currents may flow through the amplifier input pin.
2) Open circuit
If the resistance value is too high, it is like an open circuit. so although there is a feedback, it may be an open circuit.
So, how do I decide the maximum feedback resistance value? Read more

Frequency to voltage conversion – Whats the best option I have to convert frequencies between 5Khz – 15Khz into analog voltage signal varying between 1-3.3v? Read more

Help with transformer design parameters – I ordered a transformer for 48V input and 330V output. I want to know whether the provided values of the primary and the secondary inductances are okay or not? My primary current can go up to 21A. And the switching frequency is 100kHz, 1000W. Attached is the document for the specs from the factory. Also, I want to know that if the actual inductance falls short of the required inductance, then what would be the outcome? Read more

help regarding

2sc1627 and GND problems –  I’m trying to clone Vestax from an original circuit for my study project. I made the PCB but it doesn’t work properly. The question is why is the original circuit not work as it should be. Changing the transistor or supply part doesn’t solve the problem with pots. I surmise that’s it’s all about GND or supply in general. I have 2 PCBs with separate ground planes with a single-point ground connection for GND, GND1 and GND3 (the second PCB).  Maybe I misread the schematic and make a mistake with layout? What should I check or re-check, to find the problem? Read more

Does MOSFET have a pole –  Typically we say an input impedance of a MOSFET is infinity. However, there is a leakage in the oxide, so it has a resistance. Also, there are capacitors at the input.
In this case, can we say there is a pole inside a FET? Read more

Difference between four- and two-quadrant multiplier – I understand that two quadrant just has one input (bipolar) and another input to be unipolar. While a four-quadrant has both inputs bipolar. Also, a two-quad multiplier is an unbalanced modulator while a four-quadrant is balanced meaning 2-Q has carrier and sidebands while 4-Q has carrier supressed. Can anyone please explain the difference between both 2-Q and 4-Q multipliers (in terms of AM)? Read more

How to do DC sweep in Cadence spectre –  Does anyone know how to run Cadence Spectre with sweeping two input variables?  Read more

Light resistance – Ω to lux – I have a PhotoResistor of this model: Arduino KY-018 Photo resistor module. It gives me values in Ohm but I need to convert it to Lux. I have no idea how to since there’s no information on the product I bought. I tested and it gave around 1050Ω when there’s 0-10 lux. Read more

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