Sorry I got back a bit late.
Do not put DC into the AC motor. It will not work and you could ruin the motor. The DC supply which you have is to power a device such as this:http://laszpower.amazonwebstore.com/BESTEK-75w-power-inverter-car-dc/M/B003Q54V88.htm
The record player is in turn powered by the device which I linked.
The inverter must be powerful enough to power your record player and the DC supply which you have must be powerful enough to power the inverter with the record player connected and playing. If you have at least 3.5 amperes it should be sufficient. A 40 Watt inverter should be sufficient for the record player. I believe you said it was 20 Watts.
You need an inverter from the US as I would expect one intended for Europe would be 220 Volts 50 Hz. Even with the US unit confirm that it is 60 Hz and that the frequency is accurate as that will effect speed and hence pitch. Contact the manufacturer and ask. Don't trust the retailer unless they are specifically an inverter supplier. The pitch accuracy will be no better than the frequency accuracy of the inverter.
There is an other possible issue. As I mentioned the output of these cheapie inverters is a modified sine wave. What this means is that it is a stair step approximation to a sine wave such that the RMS, average, and peak to peak voltages are the same however there are only about three steps in the positive part of the cycle and three in the negative part. This results in a huge amount of distortion. Motors vary in their ability to tolerate this. My experience is that shaded pole induction motors (the kind which you will have) tolerate this reasonably well. They may buzz a little due to the stair step voltage as apposed to the smooth sinusoid of "real" AC from the power line.
If the buzz turns out to be intolerable you may have to go to a true sine wave 60 Hz AC source. These do exist but they are not cheap.
The 220 Volt to 110 Volt transformer can be useful to quick check the functioning of the player however the machine wont be useful for listening as it will run at 5/6 of the correct speed. I can't imagine that pitch error being acceptable to anyone.
Hugues TR4 wrote:Hi Phil,
Thanks a lot for your extensive reply.
Finding a 50Hz capstan motor could be a challenge indeed.
I've got a 220V to 12 V converter, meant to serve as a battery loader for several apps. But it gives DC current.
I've also got a 220 to 110 volts transformer, but I do not think it will have any effect on the Hz rate needed by the motor (or yes?)
I'm far from being an electric/electronic specialist.
So, if I understand rightly, you suggest to feed the AC motor with 12V DC current?
Please correct me if I'm wrong.