Recent content by gnurf

What's your gut feeling re the OP then, if I may ask? None of the books I've seen that go through the process of fin length optimization etc on simple fin structures such as the one in the OP, indicate or mention that covering the finned face with an insulator is a good idea. My hope here was...

While an interesting design, I fail to see how the magnetron cooling system you describe is relevant to the OP. My specific question was what happens to a vertical oriented heatsink's ability (by natural convection) to rid itself of heat if you cover the fin tip face with an insulating material...

Why do you believe that? I stated as a premise that the tips were covered with an insulating material, so surely the tip condition here corresponds to the adiabatic case from your wiki link, and not the constant temperature?

It has been suggested to me that the ability of the heatsink shown below to remove heat from its base (orange) by natural convection could be enhanced by closing the open side (pink) shown in the figure below. Assume a lid (pink) of non-conductive/isolating material. I think the idea is that...

I'm trying to understand why you made this subtle change. In practice I'd think a simple RC filter referenced to ground would do the job quite nicely, but by referencing it to Vcom I think you've now provided a more direct way to couple a fast rate of change in the DAC output voltage to the...

I visualized ¨the effect of resistor tolerance on the load current with a Monte Carlo simulation run. For anyone playing along at home, you can do this by changing the 10k values to {mc(10k,0.01)} for the 1% case and adding .step param run 1 20 1 to your model to get e.g. 20 random constalations...

Let me guess. Internal to an opamp, the level shifting is done after the amplification?

My last post was not clear. What I meant to say was that I first tried to extract the Vos from the AD8565 model by doing as I showed in the attached figure. From that I concluded that the Vos in the model was about 2mV. I was wondering if that, in general, was a viable way to get the Vos number...

Based on the model and result below, is it safe to assume that about 2mV of voltage offset is included in the AD8565 model? To see what the effect of the worst case 10mV looked like in the actual circuit, I added a 10mV voltage source in series with each negative AD8565 input (I guess that makes...

Back at it now. I'm following your lead here and I'm re-doing the whole thing. I've causally picked AD8565 in my simulation and it seems to behave OK. Not that it worried me much, but the ground noise seen in post #39 is more or less gone in your circuit. I haven't tried to analyse why that is...

See attachments. Plot with a SINE(0 50 50) source in parallel to R20: It's just a residue from earlier experimenting with different (larger) sense resistors. See datasheet p. 12 for more info. It can be ignored here. (I'll get back to earlier posts as soon as possible.)

OK, so I hacked together something which seems to do what I want which is to control the load current by adjusting the output of a DAC. What is new here, well to me anyway, is the IL300 optocoupler suggested by @Tom.G in post #19 which I think solves the issue with floating grounds mentioned by...

Yeah, the control is from a MCU, but it's a DAC output and not a PWM. I've been down the latter path already (and probably should've stayed on it as well), see post #21.

Yes, it's a heater aka an electronic load. The AD629 does indeed attenuate by 20 as you say, but the gain is also internally restored and the transfer function is ultimately Vout = V(+IN) - V(-IN), ref page 10 in the datasheet. Don't be sorry, I'm thankful for all feedback. I add a DC bias...

This looks very promising. I'll look through these and see where that gets me. Thanks! http://www.vishay.com/docs/83622/il300.pdf http://www.vishay.com/docs/83708/appnote50.pdf