Recent content by Pagedown

Thanks, Nas. The information u provided is very useful. I may go for a dc relay, if psu connected, it disconnects the batt.

so i need a relay or switch in between to switch between the supplies?

If I had a battery as backup, and a DC power supply connected to a load. And say the battery is 4.5V and the DC power supply is 5V, is the current now drained from the battery or the power supply? I am doing a project where it needs battery for portability sometimes but can have the power...

I have disconnected everything, only with neutral and the 0.1 resistor in series then to the isolation transformer. At the secondary side of transformer, I connect only my scope, and the same amount of noise exists. It is clearly because of the isolation transformer now. But it doesn't make...

The same amount of noise.

The scope tells me the same noise at the transformer secondary. Thus, I have neglected the opamp gain stage at this point.

Can a low pass filter solve this?

Okay, if both signals are same which is the common mode signal, how do I solve it?

Okay, I will try that. Thus, the purpose of this is to measure the voltage from neutral to earth?

Uart, I cannot connect the scope across the sense resistor itself because it will trip the breaker in the lab. I can only connect the scope across the 1:1 isolation transformer.

Yup, I checked the isolation transformer with a known signal across it and the outputs are directly the same. I dun understand there should be any voltage across the neutral wire as high as 0.5V as there isn't a complete loop across a wire isn't it? Unless in respect to the oscilloscope ground?

This is schematic I detect lots of noise across the Rsense although the switch is still open.

I have a sense resistor connected in series with the neutral wire. From the oscilloscope i detect noise of around 500mV - 1V across the sense resistor at high frequencies 60khz- 100khz. I see the noise once the power plug is inserted to the socket, although not switched on(live wire not...

This is my schematic, the function of this circuit is to translate voltages and currents into DC levels to be read by a MCU. It has a built in simple +5V power supply to supply components, and the voltage & current sensings circuitry. The opamp is powered by the built-in +5V and -5V converted...

It is a silicon full wave bridge rectifier. With an open circuit, isn't the primary acts like a short circuit between hot and neutral as there is only a small resistance and no magnetizing force to oppose it(open secondary)? Now the problem was trailed to the sense resistor, 0.1 ohm at the...