Electronic DC Load - Performance Improvements
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- Опубликовано: 19 окт 2024
- In my previous video I left off with the performance response time at between 500uS and a couple of mS depending on the load being switched, this was not good enough for some viewers and they let me know it. So......
How does 50uS - 100uS sound for various loads
After playing around with a few de-coupling capacitors I was able to tune the circuit better and the total cost for this 10X improvement is only anout 10 pennies or 20Cents for us north american residents. Not bad if you ask me and thanks for taking me to task on it. We have a much better design now for everyone.
In a future version 2 of this Electronics DC Load I will use Gate drivers and get it even better but at the same time, add computer control in the process
anyway, you can find the new schematics along with a post here:- www.element14.c...
Enjoy
I'm a little late to the party and you've probably got this finished by now, but a couple of thoughts occurred to me while watching these two DC load videos.
1. Given that you were testing with fast-edge signals that generated a nearly 5A step, some of the ringing you saw on the load voltage and current may be caused as much by the performance limits of your Keithley power supply, and stray inductance in the test leads, as the TLC272 and its bypassing and feedback arrangement. You might try using a decent size lithium battery in place of the Keithley, add some significant low-ESR capacitance at the DC load input, and keep the input leads short. This will provide a substantial fast current reservoir and eliminate the influence of circuitry you can't control.
2. Take a look at the LT1026 or MAX680 dual-rail charge pump converters. They would allow you to very simply generate +/-10V rails for the op-amps from the 5V output of the REF02. This would let you to reach a true zero current state by driving the MOSFET gate slightly negative, overcoming the op-amp's input offset (in fact you could switch back to the TLE272). They're both available in DIP-8, so they're breadboard friendly.
I enjoy your channel very much, Peter, and I look forward to the rest of your Modular Bench Power System series. Cheers.
Nice!!. I'm very interested in version 2. Could you make it multichannel and adding controlled discharge capabilities for 18650 batteries. That would be awesome.
A very interesting build. It's one to make. Thanks.
PS I'll wait for the final build!
wow! that is great work, It really is coming along!
Hi, Very nice and usuefull project for the bench. I am interested in doing it. Did you generate gerber files of this project ? Another question is why is that external 5v sign ?
Great help! Much gratitude! I have 3 questions:
1. Should the 10nF cap (placed in parallel with the MOSFET driver resistor) described in the video yet missing in the uploaded schematic, be included or not(which is your latest preference)?
2.I'm interested in 'simply' expanding on your design's power capacity, by connecting more 'modules' consisting of MOSFETs, shunt resistors (and any other caps or resistors as necessary) in parallel, so that I can test say a 500W PSU at say 35-40A. What do you think would be the best place to make the potential add-on connection point(s)?
3. Would this modularizing require each module to include its own (separate) driver resistor(/parallel cap) and feed back cap?
Peter, I am not sure if you have tested the CPU heatsink as yet. I am making a variation of the KerryWong.com load. In testing with 2 IRFP150 mosfets attached to an old AMD heatsink which looks identical to yours I am able to easily dissipate 250W. So the heatsink will cover you design standing on it's head. Further good news these are available locally for about AU$15 each. I was also tempted by the range of fan cooled tunnel sinks by Fischer Electronik and HL Marston from Element14. Expensive but certainly look the goods if you wish the make a compact instrument that looks the part.
Rob B just editing the video now, I easily handled 150W with a single mosfet and old CPU heatsink, it was barly above ambient temperature
Did you ever release a manufactured through hole PCB for this?
I have not, but I am tempted to re-work the design with a few additional features and perhaps look at doing a PCB as I have not done one since the days of using Black Tape and a load of patience :)
hi witch value is shout restsor?
gregor obreza The Shunt Resistor is currently 100mOhms (0.1R) but can easily be changed to 50mOhms to give a 10A range with no other changes. Just watch out for the power dissipation on the MOSFET
Hi how much power (0..50)W
Here is a similar circuit:
www.solo-labs.com/diy-30w-adjustable-electrical-load/
very similar indeed. Thanks for sharing
I toured the TEK plant in Portland in 1976 as part of a lets fix TEK consulting job. I am biased.
Screw all this one up man-ship crap in EE.
Your response frequencies were fine. Anyone needing more is a poser.
Why? Because otherwise they would be buying. They would be fired if they built.
Tell them to piss off.
Oh crap, I am getting drawn into a poser troll. Groan.
MOSFETs don't care at all about fall time ring. Rise time, under extreme voltage change, MAYBE, just maybe.
Otherwise, my very, very, large light industrial shop would have died a while back.
You want to see high frequency effects on a MOSFET, lock the rotor on a 3-phase, 25 HP motor hooked to the mains through a reactance transformer and into an ABB VFD.
BANG poser.
I like TEK, I have used them and Keysight (HP/Agilent) for well over 40 years.