The AT-S-250 Wrist Strap Tester gives you, the technician, a quick quality check as to the status of your ESD wrist straps. Fabricated in a durable, ESD-safe plastic housing, the AT-S-250  is a non-complicated, quick and easy tester for your wrist straps.

Powered by a 9 volt battery (included), your wrist strap's grounding cord/cable connects  right into the tester's grounding receptacle conveniently located at the back. With the wrist strap fastened to your wrist, press the large metallic button and the AT-S-250 provides you instant test results via the three visible LED lights on the front panel.

The AT-S-250 Wrist Strap Tester With Go/No Go Lights
And Audible Signal. Durable ESD-Safe Construction.

If your wrist strap is good, the green LED illuminates along with an audible signal. If the quality of the wrist strap is compromised, one of the two red LED's will light up. A good wrist strap is considered to be between 800K ohms and 9 Meg ohms. If the resistance is too low (below 800K ohms), the "Low" indicator illuminates. If the resistance is too high (above 9M ohms), the "High" indicator light turns will turn on.

Background: Static is easily generated by humans from just the mere movements of our clothing upon surfaces or our shoes moving upon the floor. The static charge builds up within us and we actually store the charge in our bodies. Anyone who has ever stepped across a carpet in the winter and touched a metal door knob is already familiar with the little jolting sensation and even the crackling sound that happens. Why that happens is because a stored charge within us is being released or discharged. And this is what is called Electrostatic Discharge (ESD).

While the charges that build up within us are not high voltages, they are high enough to quickly and permanently damage sensitive electronics devices used on printed circuit boards (PCB's). An ESD-Safe wrist strap (also called a grounding bracelet) helps prevent static from being discharged and from degrading chips or damaging circuits.

The ESD wrist strap is made from a fabric woven with conductive filaments into an elastic band that fits upon the wrist of the electronic technician. When connected to a grounding source, the conductive fibers within the wrist strap drain static away from the technician helping to prevent discharges thus protecting your electronic devices.

However, over time, the continuous grounding integrity of a wrist strap can wear down from dust build up, from body oils and such. For this reason, it is important to periodically test the quality of the wrist strap itself.

A wrist strap tester is your verification tool to insure that the resistance of your wrist strap is no lower than 800KΩ and no greater than 9MΩ.

Quality PCB prototyping, low volume PCB production and/or rework requires protecting your sensitive electronic devices and components from electrostatic discharges. An ESD wrist strap tester is an essential "tool" for any engineer or technician working with printed circuit board assemblies in today's world of micro electronics.