Current/voltage limiting circuit
Current/voltage limiting circuit
(OP)
I need to protect a 24 VDC system fed from a large mining haul truck for current/voltage spikes.
It's spec would range from 18-32 volts and .18 to .75 Amps.
Can anyone help me with this?
It's spec would range from 18-32 volts and .18 to .75 Amps.
Can anyone help me with this?





RE: Current/voltage limiting circuit
The simplest way (although not exotic) is to have a smaller seperate battery that operates the device and is charged through a diode and small 5 ohm resistor. Two small 12V gell cell batteries don't take up much room.
RE: Current/voltage limiting circuit
TTFN
RE: Current/voltage limiting circuit
RE: Current/voltage limiting circuit
It's pretty hard to get a voltage spike from a pair of 8D or larger batteries.
Have you considered connecting your equipment closer to the batteries?
The voltage surges are most likely generated in the supply wiring rather than originating from the battery.
Take a look at what equipment shares the supply conductors with your sensitive circuit.
Don't forget the ground circuit. A bad ground can do all sorts of interesting things.
If your circuit is grounded to the chassis rather than with a wire to a designated ground point that may be your problem.
yours
RE: Current/voltage limiting circuit
http://cache.national.com/ds/LM/LM2931.pdf
Or some add on gizmo that goes between some aftermarket thing and the vehicle?
If you need to keep a 24V aftermarket device happy at 18V then you need special equipment.
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: Current/voltage limiting circuit
The most expensive part is a PC board.
Is it supposed to be constantly ON ?
How many do you need ?
RE: Current/voltage limiting circuit
If so, then a voltage regulator (designed for vehicular systems as itsmoked suggested) and/or MOV (rated for 24 volt vehicular system) on the input may be all you need.
However, from experience I know that in some heavy industrial vehicular environments - particular near mines that vehicles can be jump-started from arc-welders or 80 volt DC mining carts (fork lifts, etc). Equipment handlers will resort to many 'unusual procedures' to keep schedule when batteries are dead and it's cold enough to gel diesel. Such situations are outside of normal "load-dump" considerations. If this is a possibility, then you need a transistor/zener circuit that opens when a certain voltage is exceeded, or a protection module. By protection module, I mean that someone, somewhere, probably had a module designed to protect devices used on an industrial vehicle - try a google search or talk to the equipment supplier for suggestions.