electrical question

[simonfraser]

i have a maplin Amp display, fuse blade on a lead to insert into the circuit to be tested. cheap as chips. i have it set up for the wind / solar input.

it runs on a small internal 12V battery.
how about wiring this supply in with the boat?

my supply runs at 12.8 to 14.4.
is it likely to work, or will it blow the display / display the wrong info ?

 

[William_H]

You need to confirm that the negative of the display is also the negative of the voltage (current) being measured. Many of the older display chips needed a separate isolated supply. (usually a 9volt battery) You can fit a battery and just have a push button for powering up to read.

If the negative is the common then you can use it for voltage and current measurement. Voltage will require a large series resistior often mounted on the board and connected by jumpers.
Current requires a shunt which you will have in series. So the negative of the supply and the negative of the shunt will be connected and you will need another wire to the positive supply.

So it is all a bit tricky and depends on the actual circuit board you have. Do you have any documentation on the display board. If not you might google the actual display chip on the board and data will tell you if it has a common negative. good luck olewill

 

[William_H]

You didn't say if it was an LED or LCD display. An LCD display will probably be OK on 14.4 volts. The LED display will probably feed too much current to the LEDs. Best use a regulator chip like 7812. However my guess is that the display is really intended for 9volts. Again check the specs for the chip. It may have a regulator built onto the board. PM me if I can help further good luck olewill

 

[simonfraser]

tnx, just seen:

http://www.maplin.co.uk/module.aspx?moduleno=10529

simple, i'll put one of those in, tnx.