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Mini analog VOM volt-ohm meter (C) Daniel Friedman VOMS: Analog Volt-Ohm Meters
Choosing & Using a VOM to Detect or Measure Electrical Voltage or Electrical Resistance & Other Values

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Analog Volt-ohm meters (VOMs):

This article describes analog or needle and dial type VOMS, volt-ohm meters used to detect or measure voltage, resistance and values.



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VOMs: analog type Volt-Ohm Meters

Simpson VOM Model 260 Series III ca 1958 (C) D Friedman Paul GalowAn analog volt-ohm meter or VOM is a multi-purpose electrical test instrument that can measure AC or DC voltage, resistance (ohms), and depending on the model current (amps).

Some VOMs can also measure sound levels (decibels) or other metrics using an appropriate attachment.

The display on an analog VOM uses a needle or pointer that rotates over display values in an arc. You can see an example of a analog display in the VOM shown at above left. That meter includes a clamp-on ammeter for measuring current. Below is a Simpson analog VOM that has been in use since 1958.

Watch out: If the VOM user is not trained in safe use of this equipment s/he should never insert any instrument or tool into electrical equipment.
See SAFETY for ELECTRICAL INSPECTORS

What's the difference between a digital multimeter (DMM) and an analog VOM or volt-ohm meter? We described VOMs just above. A digital multimeter (DMM) is a multi-purpose electrical test instrument that can measure AC or DC voltage, resistance (ohms), current (amps) and often other conditions such as sound level (decibels) or temperature by using additional sensors or probes.

The display on a digital multimeter is just that - digital, using an electronically-generated number corresponding to the range at which the DMM is set. An example of a digital multimeter is shown just belowk the display window of a Sperry DSA-500.
At DMM DIGITAL MULTIMETER HOW TO USE we explain the function and level settings and probe connections needed when using a VOM or DMM to measure voltage (as well as when measuring current or resistance).

Analog VOMs - Volt-Ohm-Milliameters

A VOM or volt-ohm meter may also be found in an analog form such as our favorite and now a collectors-item little Jensen VOM that we've used for nearly 30 years. Here our photo shows the Jensen analog VOM with its probes attached but not connected to anything.

In 30 years of use we needed one repair of this instrument - an internal fuse which we couldn't find locally. In analog VOMs such as this unit there is typically a very low-amperage fuse whose function is to protect the meter movement from damage.

On contacting Jensen Corporation, the company kindly sent us a few spare fuses. The total repair bill? $0.00.

This little VOM, ca 1985, is about 1/8 the size of the Simpson 260, ca 1958, described just below.

Simpson produces a wide range of test instruments including analog VOMs that can be used to measure resistance (ohms), direct current, alternating current, and even decibels.

See DMM DIGITAL MULTIMETER HOW TO USE for a separate discussion of digital multimeters and VOMs.

Reader Question: Speco F-70 analog VOM meter

Speco F-72 Analog VOM - InspectApedia.com27 Feb 2015 weldon said:

Where may I find wiring diagram for Speco F-70 analog VOM meter.

Reply:

Weldon, you can contact Speco Technologies at:

Speco Technologies, 200 New Highway, Amityville NY 11701 Tel: 1-800-645-5516

Currently, in addition to a range of analog VOM Multimeters, Speco produces a wide range of products besides your Speco analog VOM, including digital video recorders, secuity cameras, wireless microphones.

Unfortunately the company's technical support and contact information "... is available to authorized deales only. Contact your installe for questions regarding your Speco products."

The current product line includes an F-72 20K Ohm/Volt VOM Multimeter (shown at above-left) similar to your older F-70. If the company is unable to provide you with a wiring diagram for your Speco F-70 VOM I'd check with some of their distributors such as

Christy Industries at 800-472-2078 in the U.S.

Simpson Analog VOMs

Simpson VOM Model 260 Series III ca 1958 (C) D Friedman Paul Galow

Simpson produces a wide range of test instruments including analog VOMs that can be used to measure resistance (ohms), direct current, alternating current, and even decibels.

Shown here is the Simpson Model 260 Series III Volt-Ohm Milliammeter produced ca 1958 and in use by its owner Paul Galow since ca 1959. This VOM is much larger than the compact devices in wide use today, having a meter display width of 4 1/2".

The device is also quite durable. Mr. Galow reports having to perform two maintenance chores on the instrument, replacing a battery and replacing a soldered-in-place fuse [image] hose function is the protection of the meter movement.

Watch out: don't confuse a volt-ohm-milliameter with clamp-on ammeteres (described next). The Amps measurement range of this Simpson Model 250 VOM is 1MA to 500MA - not at all in the range of household appliances or larger equipment. For higher ampacity measurements you will need an ammeter such as the device described just below.

See this circuit diagram [image] of the Simpson 260 VOM.

See DMMs VOMs SAFE USE OF for safety procedures that also apply to use of VOMs

Where to Buy a DMM or VOM
List of Electrical Test Instruments, VOMs, DMMs, Voltage Detectors: Manufacturers & Sources

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