tpetar
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What do you folks think of this tip?If you need to measure current with that multimeter use a small resistor (small in resistance, large in wattage) in series in the circuit, and a voltmeter in parallel with the resistor. The rest is Ohm's law.
What do you folks think of this tip?
Might be the easiest option but it is not really a safety issue as I don't have plans to ever test mains voltage. I am only using the DMM for electronic circuits.You could just run some wire from the internal fuse terminals outside the case and mount the clip there, but that could have potential safety issues if you don't cover it. You could also just tape your screwdriver and a bag of fuses to your DMM so it's always handy when you need it.
Might be the easiest option but it is not really a safety issue as I don't have plans to ever test mains voltage. I am only using the DMM for electronic circuits.
You could also just tape your screwdriver and a bag of fuses to your DMM so it's always handy when you need it.
Voltage drop can be an issue. But I can insure you from current measurement practice in industrial instrumentation, that it's really hard to keep up with the accuracy and long term stability of a simple shunt (like it's shown in the photo) without referring to expensive and bulky compensating current transducers.Current shunt have influence on current in whole circuit. Inside some DMM you have shunt. Better variant is hall sensors.
Voltage drop can be an issue. But I can insure you from current measurement practice in industrial instrumentation, that it's really hard to keep up with the accuracy and long term stability of a simple shunt (like it's shown in the photo) without referring to expensive and bulky compensating current transducers.
Taster? SMD?
... it is not really a safety issue as I don't have plans to ever test mains voltage ...
jasonc2 said:- "It's OK because I don't ever have plans to <insert unforeseen future here>" is not a good thought process in general.
- It's the current that gets you. Dry healthy skin has enough resistance to protect you but an interesting factoid: https://hypertextbook.com/facts/2000/JackHsu.shtml
- High current most definitely does not lie solely in the realm of mains. Also, if you're constantly blowing fuses you at *least* know that you're frequently running more than the fuse rating through the cartridge.
- Besides, you don't know you're testing e.g. "mains voltage" before you test it. That's why you're testing it. You wouldn't want to e.g. discharge a power supply capacitor into a sweaty hand, or run a transformer ac current through your palm and find that you can't let go of it - you only need about 5-10mA ac to get through your skin to cause muscles to contract and lose control.
Right. And this is a PTC self-resetting fuse:So I don't have to open open it up to change the fuse.
What rating was the original fuse and what was the rating of the PTC fuse you replaced it with?
Erikl, are you sure the PTC is a MOV? MOV is a high voltage clamping device (like a zener diode), not current limiting device. A PTC current limiter device works generally by having pieces of carbon touching inside a special plastic matrix (the "polymer" part of the polyswitch name). Current is carried through the carbon pieces. When the carbon gets hot due to excessive current, the plastic matrix expands and the carbon doesn't touch anymore - no current.
S1 is taster. Just one hole drilled on multimeter plastic case.
Thyristor, transistor exist in SOT23 SMD case.
Resistor in SMD lets say 0805.
I hope that you didnt mean really to put 2n3055 transistor for this.
Dont let that this resseting fuse be bigger then multimeter. Yes you can also use TO92.
S1 is taster - You lick it to reset the circuit?
I should tell you a story about the Transportation Safety Administration here in the US. I was shipping some 10cm dia x 20 cm long capacitors in my baggage for a test I was doing at a customer site. The TSA pulled my box and called me back to the check-in counter because they were concerned about the energy storage in the capacitors. TSA told the airline that it was their decision whether to accept the parts for shipment. I finally got the airline to accept the box after I licked the capacitors to show they were discharged.
eBay seller said:There you go again: replacing that wimpy 5A fuse with another 5A fuse, knowing full well that it's gonna blow just like the last one. What you need is a fuse that will give your circuits the fortitude to withstand those transient high-load moments -- a fuse that won't simply melt away -- a fuse that will carry current even as smoke pours from your electrical goodies. What you need is 7.5 Amps!
Just because your electrical system was supplied with insulated wiring doesn't mean it has to stay that way. What is the #1 reason why small wires can't carry "big current?" Well, with all that insulation covering them, your wires simply get hot and melt. Your wiring needs plenty of fresh, cool air so your circuits can dissipate excess heat. Consider the electric company. Sure, they insulate wires attached to houses because they know some safety freak would complain. But when they leave the populated areas and start across the wide open spaces where nobody really cares, what do you see strung between the poles? Bare wires!
Now you can discover the "bare wire advantages" enjoyed by utility companies for decades. Simply replace those inadequate little fuses in all your circuits with these. If you accidentally pop one, put in two the next time. Or three. Or wrap some aluminum foil around the terminals. Then put some additional load on the circuit. Sure, it smells bad for a while, but you'll soon be free from that useless insulation once and for all.
Dear all: Please hire me for freelance work so that I can afford my own airplane, fill it with the entire world's stock of 200mA fuses, and also turn my childhood dream of running an uncharged capacitor transportation and logistics company into reality.
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