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History of the manufacturer  

Ecos Electronics Corporation; Oak Park, IL

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Name: Ecos Electronics Corporation; Oak Park, IL    (USA)  
Abbreviation: ecos
Products: Model types

Ecos Electronics Corporation
205 West Harrison St.
Oak Park, IL  60304

Manufacturer of test equipment circa 1980's - 1990's.


In 1971, Peter Portoulas of Chicago, IL, applied for a US patent on an outlet testing device described as:

"A three wire ground type AC outlet tester for testing (1) the correctness of socket wiring of three-wire receptacles, including neutral-ground reversal or shorting errors, (2) the magnitude of electrical impedance in the ground circuit, and (3) the existence of undesirable excess voltages, the tester including signal injecting means for injecting a test pulse into the ground-neutral circuit, a threshold detector responsive to a sensed magnitude value for responding to the amount of impedance in the ground circuit, and indicating means energized for indicating the presence of an amount of impedance in the ground neutral line which exceeds pre-set threshold impedance levels. The tester includes means for positively indicating an improper reversal or shorting of ground and neutral connections at the terminals of a test outlet and further includes means for providing a distinct indication of either an open ground or open neutral wiring error."

The patent was granted in 1974 and assigned to Ecos Corporation of Chicago.

In 1972, Jacek Antoni Persidok of Chicago, IL, applied for a US patent on a method of measuring impedance in a noisy environment.  The description on the application is:

"Method and apparatus for measuring an unknown impedance in the presence of extraneous signals by injecting into the impedance to be measured an oscillating current signal, which may be modulated, generating in the unknown impedance an oscillating voltage signal, applying the generated signal and any extraneous signals present in the circuit under test to a switch which is keyed by the injected current pulse so as to conduct only during the times the injected pulse has a given polarity, thereby producing through the switch a signal of a pulsating nature, and filtering the pulsating signal to produce a DC voltage, the magnitude of which is a measure of the unknown impedance."

The patent was granted in 1973 and assigned to Ecos Electronics Corporation of Chicago.

The two patents listed above appear to be the basis for an AC outlet tester manufactured and sold by Ecos.  They may have had only one product.

In 1984 Ecos filed an anti-trust suit against Underwriters Laboratory in an attempt to get them to change standards so that simple, low cost, outlet testers could not be UL listed.  Their lawsuit failed.

In 1999 the company was listed in Oak Park, IL, with 22 employees.

The company appears to have gone out of business around the year 2000 since another company was at their Oak Park address in 2002.


This manufacturer was suggested by Jay Kinnard.

Some models:
Country Year Name 1st Tube Notes
USA  84 Ground Check 7100A