12 to 15 V

I have a transmitter 4-20 ma which needs 15-30 C dc to work. I have only 12
V available. Can anyone please suggest a easy solution? Some small device to
solder on top if the transmitter or other solution.
I'm not much into electronics
Kindly
Ingvar
Norway.

 

I have a transmitter 4-20 ma which needs 15-30 C dc to work. I have only 12

If all you need is 20mA or so, you could use a 555 as a voltage doubler. Make
sure an unregulated power supply won't make any difference (it usually doesn't
for 4 - 20 mA supplies).

http://www.reconnsworld.com/power_voltdoubler.html

Good luck.
Chris

 

Put 3V worth of batteries in series with what you have
or buy a 15V supply.

 

Put 3V worth of batteries in series with what you have

I thought that doing this type of thing was stuffed up because of difference
in currents or something like that...
Not sure...
Ah well...
Maybe someone else knows better.

Andrew Howard

 

try "boost regulator" at Google

 

It will depend on the nature of the power supply you are using. It
may be that it is internally adjustable to give you slightly more
voltage, or it may be that working into a relatively high impedance
it will provide higher output voltage. On the other hand, neither of
these may be true.

If you could provide the group with some more information regarding
your power supply, we may be able to come up with a realtively simple
solution which doesn't include much construction.

Apart from that, you might try ordering a DC to DC converter. The
NMF1215S, 12V to 15V converter provides 67mA output curent,
sufficient for your requirement. You can get it from RS Components in
he UK or from any well stocked supplier. It's small and you will be
able to mount it on a bit of strip board or just wire directly to the
terminals.

Regards

John

 

Then what are you doing working on the stuff? ;-)

More seriously... If you don't mind doing mail order, Jameco
Electronics (www.jameco.com) sells a DC/DC converter from MeanWell. It
takes 12V in and puts out 15V at a couple of amps. Should be more than
adequate for what you're describing. I use one myself to drive a mobile
computer display.

 

'Ello.

Hmmm... 12V is 80% of the way there, you might be lucky and it might
work okay without any extra hardware.

Also, what kind of power supply are you using? If you're using a car
battery then they tend to be slightly more than 12V (maybe 13.8V?)

Finally, if you use a cheap'n'nasty unregulated mains power brick (a
"wall wart") then they tend to give more than the stated voltage and
merely rely on the load to bring the voltage down. If you're only taking
up to 20mA then I reckon that the power supply voltage would stay well
above 12V.

Hope that helps!

Ben
~~~