[Top] [All Lists]

Re: [Amps] SB220 Meter blown

To: "" <>
Subject: Re: [Amps] SB220 Meter blown
From: Adrian <>
Date: Mon, 18 May 2020 20:03:44 +1000
List-post: <>
The shunt resistor is across the meter to set the working range of application for the FSD corresponding to the full range of measurement.

, that's why it is called a shunt resistor. The protection diodes are in parallel, and so is the meter.

Your statement is technically incorrect.

Maximum Forward Voltage Drop per element at 1.0A DC -*1.1*V Once it shorts VD falls closer to zero.

On 18/5/20 6:59 pm, Steve Thompson wrote:
Rich was talking about putting diodes across the current measuring resistor, not directly across the meter itself. Typically the resistor generates something in the region of 0.5-2V which the meter reads via a series resistor.

Most moving coil movements need less than 10mA and less than 0.2V to go to full scale. A meter which reads higher current without external resistors will almost certainly have an internal shunt. If you're trying to protect a meter with an internal shunt you probably need to look at the biggest Shottky diodes you can afford as they conduct at  lower voltages than silicon ones.

At 20+A glitch current, the voltage across a 1N5400 type diode will be in the order of 1.5-2V.

Steve G8GSQ

Amps mailing list
<Prev in Thread] Current Thread [Next in Thread>