Checking RPM On Cassette Motors - UK Vintage Radio Repair and Restoration Discussion Forum

camtechman · 6th Dec 2016, 1:03 pm

As many of you know, one of my passions is cassette recorders.

Over the years I have accumulated many different motors, some of which I know the specs but sometimes I have bought motors that I don't know.

With these unknown spec motors I'd like to know if there's an off the shelf instrument for measuring the RPM.

Cheers,

Tony

Station X · 6th Dec 2016, 1:10 pm

You can get automotive type rev counters which work by shining a light beam onto the flywheel to which a piece of reflective tape has been stuck. They count the number of reflections in a given period and display the RPM digitally. For slow running engines two or more pieces of tape can be used and the reading divided by two or W.H.Y.

You may be able to attach a cardboard disc to the motor and do something similar.

The devices can be found on eBay. For example:-

http://www.ebay.co.uk/itm/Digital-LC...sAAOSwubRXMZwx

60 oldjohn · 6th Dec 2016, 2:41 pm

That is what I use, but never on anything as small as a cassette motor. But I expect it will work well.
John.

camtechman · 6th Dec 2016, 8:14 pm

I'll be checking the item suggested, thanks

6th Dec 2016, 8:26 pm

Model aircraft ones can be cheaper.

camtechman · 10th Dec 2016, 2:45 am

Do you have any information on this type?

Thanks,

Tony

percival007 · 10th Dec 2016, 8:55 am

Hi,

have you tried Googling (other search engines are available!) the info (if any) written on the motor?

A quick Google of a Motor I have lying around revealed its datasheet.

James.

http://www.datasheet4u.com/datasheet....php?id=830308

Herald1360 · 10th Dec 2016, 10:03 am

It might be worth scoping the motor current. There should be something in it which is harmonically related to the rpm frequency.

6th Dec 2016, 1:03 pm	#1
camtechman Nonode Join Date: Jan 2008 Location: Milton Keynes, Bucks. UK. Posts: 2,552	Checking RPM On Cassette Motors As many of you know, one of my passions is cassette recorders. Over the years I have accumulated many different motors, some of which I know the specs but sometimes I have bought motors that I don't know. With these unknown spec motors I'd like to know if there's an off the shelf instrument for measuring the RPM. Cheers, Tony __________________ When I die, please don't let my Wife sell my collection for the amount I told her I paid for it!

6th Dec 2016, 1:10 pm	#2
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,288	Re: Checking RPM On Cassette Motors You can get automotive type rev counters which work by shining a light beam onto the flywheel to which a piece of reflective tape has been stuck. They count the number of reflections in a given period and display the RPM digitally. For slow running engines two or more pieces of tape can be used and the reading divided by two or W.H.Y. You may be able to attach a cardboard disc to the motor and do something similar. The devices can be found on eBay. For example:- http://www.ebay.co.uk/itm/Digital-LC...sAAOSwubRXMZwx __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

6th Dec 2016, 2:41 pm	#3
60 oldjohn Dekatron Join Date: Dec 2004 Location: East Yorkshire, UK. Posts: 3,987	Re: Checking RPM On Cassette Motors That is what I use, but never on anything as small as a cassette motor. But I expect it will work well. John.

6th Dec 2016, 8:14 pm	#4
camtechman Nonode Join Date: Jan 2008 Location: Milton Keynes, Bucks. UK. Posts: 2,552	Re: Checking RPM On Cassette Motors I'll be checking the item suggested, thanks __________________ When I die, please don't let my Wife sell my collection for the amount I told her I paid for it!

6th Dec 2016, 8:26 pm	#5
Guest Guest Posts: n/a	Re: Checking RPM On Cassette Motors Model aircraft ones can be cheaper.

10th Dec 2016, 2:45 am	#6
camtechman Nonode Join Date: Jan 2008 Location: Milton Keynes, Bucks. UK. Posts: 2,552	Re: Checking RPM On Cassette Motors Do you have any information on this type? Thanks, Tony __________________ When I die, please don't let my Wife sell my collection for the amount I told her I paid for it!

10th Dec 2016, 8:55 am	#7
percival007 Heptode Join Date: May 2005 Location: Oxfordshire, UK. Posts: 852	Re: Checking RPM On Cassette Motors Hi, have you tried Googling (other search engines are available!) the info (if any) written on the motor? A quick Google of a Motor I have lying around revealed its datasheet. James. http://www.datasheet4u.com/datasheet....php?id=830308

10th Dec 2016, 10:03 am	#8
Herald1360 Dekatron Join Date: Feb 2007 Location: Leominster, Herefordshire, UK. Posts: 16,535	Re: Checking RPM On Cassette Motors It might be worth scoping the motor current. There should be something in it which is harmonically related to the rpm frequency. __________________ ....__________ ....\|____\|\|__\|__\_____ .=.\| _---\__\|__\|_---_\|. .........O..Chris....O