Analog Top Talks in March 2019 on EDABoard.com

Peer-to-peer, engineer-to-engineer questions and answers from the EDABoard.com engineering community around analog ICs and analog design. Click the “Read more” link and follow the entire conversation and maybe add your two cents by logging in to EDAboard.com.

Contactless water level sensors – I’m making a water level controller project. So far what I’ve done:
– the water I’m dealing with is salty water, too much scaling
– I’ve built a water level sensing circuit with normal probes. Due to scaling they stopped working
– I used stainless steel probes they also stopped working after a few days  all because of scaling (salt water)
– I used floats with reed switches. Due to extreme temperature conditions the reed sensors glass tends to fuse/break. Read more

Problem with solar panel charger – I have built a circuit that is supplied by 12 V, 560mA, solar panel, I have modified the solar charger circuit you see on the attachments (solar-charger-550×274), and I conclude to the circuit. I did this from suggestions I got, and because the “solar-charger-550×274” didn’t work. Read more

 

 

 

 

 

 

Problem with oscillation on receiver audio stages – I have tested this AF amplifier after the mixer stage of a direct conversion receiver that uses a diode mixer. It does not have the output volume I seek (not too loud). But when I increase the gain of the TDA7052 bad audio oscillation happen. Read more

3 phase 3 wire measurement – I am trying to build 3-phase voltmeter that could measure L-L and L-N voltage during 3-phase 3-wire, and 3-phase 4-wire connection. 3-phase 3-wire and 3-phase 4-wire connection are external connections. In 3-phase 4-wire we will get a neutral reference so we can get an accurate reading for L-L and L-N. But in case of 3-phase 3-wire we don’t have a neutral reference. In this case, it will be difficult to get a gnd reference. I would like to use both connections. Read more

Power amplifier delta and K factor <1 –  I would like to design a power amplifier with transistor CREE CGH40006S If I want to match impedance and it is always not matching, does it affect the stabilizing circuit? Read more

Powering a mini pump using a GPIO pin – My raspberry GPIO pin generate 3 V 40 mA and I am wondering if I can use a booster step up to power up a mini pump (12v 0.5a) using the GPIO pin with this booster step up without using the relay and a new outside power source. If it is impossible can anybody tell me if there is a way to power my mini pump with the GPIO pin without using another power outside source? Read more

Deriving MOSFET differential current expressions – Could anyone help to derive a MOSFET differential current expression (9.4)? (Screenshot taken from book “Low-power-wireless-communication-circuits-and-systems-60GHz-and-beyond”). Read more