A DIY Current Source Demonstrating Ohm's Law - DC To Daylight
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- Опубликовано: 7 июл 2024
- In this episode, we take a look at the shortcomings of measuring low resistances with a standard digital multimeter. We demonstrate measuring a small resistance using both the two-wire and four-wire kelvin methods. Then we build a standalone current source that will be used in conjunction with a standard DMM, allowing us to make four-wire measurements, without an expensive benchtop meter: bit.ly/30t9dKj
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#0:00 Welcome to DC to Daylight
#4:33 The Circuit
#7:51 Build It
#10:39 Test It
#12:00 Give Your Feedback
#ohmslaw #currentsource #DIY #4-wiremeasurement 
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The prototype solution is excellent , I have never seen before,.
The parts where the maker says "The issues I faced were" are my absolute favourite
Thanks. Very helpful. Quite some work and dedication you put into this video.
More of this guy in my future watch history. Very nice
Great explaination of the 4 wire measurement, I've never dug into why that was needed before.
You should fit the diode before the capacitors, if that is a 22uf electorlytic it is not protected from reverse polarity.
Facepalm. Rookie mistake - you're absolutely correct. Let's just call that cap a "reverse polarity notification device"! 😉
The prototype method is a great idea. Beats veroboard or matrix board for smaller circuits.For quick small circuits I have used stiff cardboard and a pin to make the component holes. Just push component through the cardboard and bend leads at back and solder. Great video, very well put together and educational.
Today I learnt new idea to prototyping thank you sir really appreciated
Use Enhancement mode FETs to switch in resistances. Your minimum resistance is 5000 mohms and the RdsON of 4mOhms if you were using a 2n6661 would be insignificant by comparison worst case (0.08%). It would also be consistent (wouldn't change from switch click to switch click). Using a push button, a schmitt trigger in to a toggle flip flop to a 4066 would let you do this "the old school way". You could do it all in a PIC chip for a more modern take.
Great presentation style. Excellent work!
LM317 is cool. But boy I wish someone would make a Keathly 225 knock-off with modern parts and decent accuracy. It can't be that hard right? Right?!?!? (hehehe)
how big are the lead, contact, and jack resistances compared to 10 Ohm resistor, in most cases?
@7:14 2,270 ohms? Not 2,027? TY great video and info.
Hi I have made the circuit of LM317 on bread board. I am generating a constant current of 100mA. The input to the regulator is 3.3vdc. 100mA constant current is fed to a resistor of 100 ohms. I should measure a voltage across resistor of =10mA x 100= 1000mV=> 1V, but the voltage across the resistor I am measuring is 3.3vdc. why so? I want to use the constant current source to find the unknown resistor using current and voltage How can I do this?
How high is Vin?
Hi