Recent content by coinmaster

Could I practically double the strength of a 4''x 0.5'' 35lb strength neo bar magnet using this method without overheating? Current supply isn't a problem for me, assume I have unlimited power for now, but I need to keep the added dimensions to a minimum so I don't know if i can pack that much...

Does that mean the field will be stronger but not bigger?

If I wrap a coil around a bar magnet and shoot current through the coil so that the magnetic field of the electromagnet is at the same polarity of the bar magnet will I have amplified the magnetic field of the bar magnet maintaining the same magnetic shape but bigger/stronger?

What happens if I for example, connect an Earth referenced bias voltage to the gate/grid/input of a mosfet/tube/opamp that uses a floating power supply? Does the bias simply not work or does the circuit somehow become Earth referenced?

I'm sure :-p

Um, I would love to give you a schematic but this is for a product I've spent countless hours on developing so I'd prefer not to. I don't think there is another way though, it's a difficult hurdle to get around.

Optimally, under 1 ohm. Basically as far low as possible.

I just did a quick reference of an LDR datasheet, It showed a 5pf capacitance. Doesn't seem like enough to affect the frequency response, the mosfet has more gate capacitance. The problem is LDRs don't have a low enough on resistance. I'm wondering if I use an extra bright light source I can...

Edited.

Source follower sets the bias voltage for the load. I need to adjust the AC signal as well, hence my problem.

I tried using a mosfet in LTspice in parallel with a resistor to create a variable resistance but for some reason it never reaches the source voltage when the resistance becomes zero. For example if the source voltage is 100v then at zero resistance the other size of the resistor should be 100v...

Audio frequencies. The application is an amplifier where I need an adjustable impedance at a DC bias point. The DC adjustment will be done via a source follower but the signal needs a separately adjustable attenuation.

Hmmm, voltage requirements will probably be very wide, from -600 to 0v maybe. Current will be 0-100ma.

I need a variable AC attenuator and the only thing I can think of is an LDR. However I would need the on resistance to be very low, less than 10 ohms. I've only found LDRs with on resistances of 100ohms minimum. Is it possible to go lower than the listed minimum is I use a really really bright...

I was a skeptic too before I tried it myself, there's no denying it now. I find that typically the skeptics are people that haven't done much or any personal testing themselves. Are you implying the set-up in my question won't work?