Power supply for bike

 

Thought of asking this in this forum because I know alot in here have
a decent electrical background.

I have an exercise bike that uses 4 "D" alkaline batteries for its
desplay unit and to drive a motor inside for adjusting the drag of the
bike. The unit also looks to have a external power supply jack.

However the manufacturer supplies no such external power pack. There
is no rating as to what the input would be.

I can assume because there are 4 D cells that the voltage is max @ 6V.
How would I figure out what the mah rating should be on a power pack?
I would like to use one of those plug in step down type packs. IE:
120v to about 6v .

I've taken a reading at the jack I think is for an external source and
it reads about 5 volts with used batteries.

Can anyone supply info in this area or direct me to a good website
with such info?

Thanks,

Hoopy


PS: This bike uses batteries quite quickly thats why I wish to
convert.

 


hoopy@blahblah.net wrote:


Did you look at the little plate where it gives the model and serial
number and all that? Sometimes it says there. "Input 6VDC, 500ma" or
something


Or 1.5V at a higher amperage, but yes, likely nominal 6.


To add a layer of complexity, you also need to know polarity. ie, which
part of the plug is positive, which negative. There is not a "standard"
in power adapters.


If it reads +5, then you have the positive lead on your voltmeter on
the positive part of the adapter plug. If it reads -5, you have it
backwards.
On the power adapter, you'll see a picture like a "C" with a dot
inside, and to either the dot or the C, it will say "+" or "-".


RadioShack, probably, for getting the transformer. The next question is
whether it will work with the batteries in it, and the last, what
milliamperage you need.

Did you try calling to get another copy of the manual? It would
probably identify the transformer you need.

DJ

 

Heres the funny part about an external for this bike.
The original manual lists no such power adapter. The main website
doesnt list one as standard either.

However I did find a third party part suplier that list a external for
this bike.

However..no picture is given and no specs on said device. I have
emailed the third party supplier with no feedback yet. I am leary
about buying from this vendor without more info.

As for making  or adapting one myself I fairly confident about getting
polarity right...its the millampres that confuses me.


Hoopy

 

Maybe what I should be asking is what do 4 d batteries deliver as far
as milliampres. Should I exceed this in an external power source.

I would think that the external should be at least rated the same as 4
d cells or more....Is this right?


Hoopy

 

hoopy@blahblah.net wrote:

4 D cells can supply a couple of full amps, though not for long.


What you can do is this...
Take a slip of plastic or paper and stick a couple of patches
of copper foil, tin, or anything conductive, to each side with
bits of wire attached. Slide this between the contacts of two
of the D cells. Hook the wires to your favorite multimeter when
it's set to read Amps. Use the various features of the bike and
read the meter to see how much power it draws. You may note that
it takes more power to say, move the motors, than at other times.

You might also try measuring the resistance between one contact
in the battery compartment (without the batteries in there) and
one contact of the external power jack. You may find the external
jack is, more or less, wired in parallel with the batteries.

Anthony