0
Can an ohmeter measure the value of a resistor when it's already in the circuit?
Wiki User
∙ 13y ago
It can be difficult to directly measure a resistance while it is in circuit. Generally, other parts of the circuit will have an effect on the readings an lead to errors that are difficult to predict. If the other parts of the circuit are understood, it may be possible to calculate the total theoretical resistance from the component values and then compare it to an actual reading. This is often unreliable because it doesn't prove that a specific resistor is a certain value.
It is almost always better to power the circuit and use a voltmeter to establish the voltages at different points in the circuit. If the circuit is understood, voltage readings can often show faults in resistors or other components very quickly. Alternatively, voltage readings can be used to ascertain a resistance value if it isn't marked.
Whatever the task, there is always an amount of detective work and the route to take depends very much on the circuit, hence there are no specific examples mentioned here.
Wiki User
∙ 13y ago
Add your answer:
Earn +20 pts
What is the circuit diagram on how to convert galvanomeer into ohmeter?
Just connect a resistor and a small battery in series with the galvanometer,change the markings on the meter's scale, and you have an ohmmeter.
What instruments used in measuring current and voltage?
Multi meterAnswerInstruments that measure current are called ammeters, and instruments that measure voltage are called voltmeters. An instrument that measures resistance is called an ohmmeter. Each of these functions can be combined into one instrument, called a multimeter.
How do you identify primary and secondary winding without using an ohmmeter?
use the charlie crabtree, simple really. attach the charlie crabtree to the charlie crabtree then simple turn the crabtree to the ohmeter and viola you have charlie crabtreeAnswerIf you are able to see the conductors, then the higher-voltage windings will be thinner than the lower-voltage windings.The terms, 'primary' and 'secondary' have nothing whatsoever to do with the voltage-ratings of the windings. The primary winding is the winding connected to the supply, and the secondary winding is the winding connected to the load.
How do you check a varistor with a ohmeter?
you need a very fancy ohm meter if you dont have lotsa $ perhaps an ammeter a voltmeter and a variable current source would give reliable answers maybe a megger since the ohm scale is 6v and the megohm scales use 2500V 1000V 500Vbut this is a lott poorer answer since 1000 ohms is 0 on the megohm gigohm or 100gigohm scale maybe a hipot tester depending on the low voltage and current settings this is very effective with mov's since they are usually concerned with higher voltages
What meter is used to bench test a motor for a short or an open winding?
An Ohmmeter or the ohms function on a typical multimeter would be used to bench test a motor for a short or an open winding. First, be absolutely certain that the motor under test is disconnected from any mains. Using a low ohms scale, x1 or x10, one would expect to see some resistance across the motor. The resistance can be quite low depending on the size of the motor, but should not be zero. If it is a motor that has brushes and a commutator, rotate the shaft, with the meter connected, through a full revolution. This rotation could help identify a single defective winding in the rotor. To check the stator, remove one of the brushes so that the measurement current only passes through those windings. Of course, it would help if you have a known good motor of the same kind so that you can compare the readings.
How do you measure resistance in series circuit?
Using an Ohmeter open either end and follow above advice
What is the circuit diagram on how to convert galvanomeer into ohmeter?
Just connect a resistor and a small battery in series with the galvanometer,change the markings on the meter's scale, and you have an ohmmeter.
How do you measure with Multimeter a motor or integrated circuit IC for failure?
The voltmeter function if the circuit is energized or the ohmeter function if looking for short or open circuits
How measure the value of resister?
To measure the value of a resistor, apply a voltage and measure the voltage across the resistor and the current through the resistor. Use Ohm's law: Resistance equals Voltage divided by Current. Start with a small voltage and increase gradually until a reading is obtained, but be careful that the power dissipation (watts = volts times amperes) of the resistor is not exceeded. Simpler solution: Use an ohmeter.
Does an Ohmeter that has an infinite reading indicates an open circuit?
Yes, or a circuit with a resistance higher than the capability of the meter, which would be unusual.
How do you find out the un known resistance value?
1.Use of ohmeter. Connect the ohmeter terminals to the the ends of the unkown resistance and take the reading. Adjust the range to give a good accuracy. 2. Use of colour codes. This applies if the unknown resistance is of a resistor with visible colour codes on it.
How can you measure resistance by using resistance thermometer?
You use an ohmeter. It sends current through the wire to determine value.
How did you check the electical resistance of the headlight earth connection?
Ohmeter connected both ends ground circuit. Usually this circuit very short with minimal resistance due to that. Do you have a good solid ground?
How do you test a blower motor on a 1997 Jeep Cherokee to determine if the resistor or the motor is bad?
spin the motor, if its raspy or rough, any play in it, replace it! i should have done that first! i went through 2 resistors. im bummed!
Why is the secondary of a transformer a short circuit?
If you are saying that the secondary (output) winding on a transformer seems to be a short circuit, it is very likely to be low resistance and may only be a few ohms if you measure the resistance with an ohmeter. The only way it would actually be a short circuit is if something has been inserted which has shorted the wires or it has overheated and burnt through. In which case there should be an acrid smell. Or if you can see the wires you would see they were burnt. A short in the circuit it is powering could cause the transformer to overheat, burn out and short.
How do you find Omh's?
Resistance is measured in Ohms with an ohmeter.
How do you test a horn relay in a 1993 Plymouth Sundance where the relay clicks when button is pressed but horn doesn't sound?
Relays can be a pain sometimes. There are two acceptible methods for checking relays ( that you can do at home anyway) the first and easiest is to simply swap it with a known good relay of the same specs. if this is not possible then the only other way is with an ohmeter ( a quality multitester is a must have for any do it yourselfer). compare the suspect relay to it's connector there should be four wires, two thin (control circuit) and two thick (power circuit). you need to connect your ohmeter across the power circuit. and connect a jumper wire to each control circuit terminal. connect one jumper to the ground post on your vehicles battery and touch the other to the positive for no more two seconds at a time while watching your ohmeter. If the relay is working properly you should have less then one ohm showing. if the reading is high, or the tool does nothing, you've found you're problem, otherwise, start following wires and checking for voltage, or check the whole system by jumping the power circuit. check the control circuit with an ohmeter, turn the switch on with battery disconnected and key in run position and check ohms across the relays empty connector, more than 2 ohms means a short or bad connection. good luck and be careful out there eh.. PS... use a stick or something between the horn and seat to keep the switch closed while you check the control circuit ( one person can bleed brake systems with this technique).
