Narrow-Bandwidth Television Association

Ok i tried both ideas in the last posts .

First the magnetic amp DC load circuit with the extra 2 diodes the result was the motor just ran as in if i just supplied a DC to it with no control disconnecting the control voltage did nothing so tried my resistor wheel in series with the motor it got to the point where the motor would stop but again the the control voltage seems to do nothing ....so that was epic fail

Also tried my first idea grounding the negative of the motor and using my resistor wheel in the AC load again i got the same result as above motor running full speed no control .

Going back to the first go that works i think i will look more closely at the control voltage as a higher voltage here the faster the motor turns ,so looks like i will have to see how it gos with that higher setting i have now or try another transformer for the dc power supply Oh well got go with what works.

I wanted to try this experiment as playing around with other transformers and such on the motor control when i changed transformers i was finding some transformers didn't work for me more than likely some thing i have done

But i wanted to tried and repeat some of the experiments i have read about to see what i am doing wrong .

So starting here to see if i could repeat this one as it uses no diodes ...

The results i found was not what i expected from the control winding .

Just short the 109 ohm control winding the light gos fully on or i should say best this transformer lets it do .

I might post the video of the test so come back to this post

A resistor across the circuit you have adjustment but the 28 volts coming out of that winding will do your pot in ! thats just using a pot no voltage at all.

A voltage to control the light was interesting i don't have a variable power supply test yet but it needs very little voltage to have the same effect as above ...No difference between 5 or 12 volts no increase in light one more than the other also no more or less and just short the winding ....

I am going to try the diode circuit i am using now on the motor and see how this controls the light via this transformer .and .i want to see why the DC load circuit didn't work for me first go ....

One good thing i found out you don't need big transformers for this .

I am pretty happy now with some experiments working out a magnetic amp Dc motor version 2 or 3 now controller .

Heres a video to prove i can be messy at construction testing as well

The first circuit in the drawing top left using one diode for the DC motor worked ok but to much Ac coming out the primary of the transformer seemed a bit much for the pot to control ....with an open primary the motor gos full speed when primary is shorted the motor stops and the light globe gos on .

The second circuit i have removed the light globe again primary open motor gos full speed and you short it motor stops , using pulsating DC current to flow through the coils sort of halfs the problem of the Ac out the primary .

With a 1 meg pot across the primary you can control the motor speed from full stop to full speed .

I found no need for a voltage to control this i suppose the effect of the transformer stepping up the voltage the voltage is there but being AC controlling this amount it has the same effect as connecting a dc voltage to this pot then to the primary of the transformer .

From the experiments i have read about they tend to use 2 transformers so this might be a bit different .

Experimenting with the reflective disk idea i found The LDR with out amplifying is to weak i then tried light chopper idea cutting out the slots and placing the partly cut out disk between to clear disks ,i can see this might work looking on my scope but i am again in a catch 22 it still needs amplifying by the looks of it and i don't want to do this with a valve or solid state problem is for a magnetic amp you need a AC at that frequency to amplify that frequency ...time for rethink .

Testing some steppers just turning one by hand quick i am getting around 2 to 3 khz on a very fine step stepper motor i have.... this may be more promising working on a generator idea + i should be able to get a nice voltage out of it i will test if i can use the magnetic amp motor controller on the AC generators dc motor .

May turn the that strobe disk idea into a monitor for testing ,i am very keen to see what i can get out of this stepper KHZ wise ...

Looking my junk motors i came across 2 different DC motors with 4 wires ,i tested one as you see the other 2 wires pump out AC the motor i tested at 5 volts gives over 380 hz at 12 volts as you see in the picture gives over a khz
Wonder what these type of motors are called ? if you adjusted it to 400 hz you pretty much have a built in encoder clock ? mmm i know i had some thing like this i used in a past monitor motor out of a vintage laser disk player but never used it .

Edit ...with the stepper shown i made a little dc motor driving the generator so far results over 4khz almost at the SSB bandwidth with direct drive with a pulley i might be able to get some more nice bandwidth..

They both look like bipolar steppers to me. There is a vague chance that the last one is a servo but I doubt it on the basis that they are almost unheard of in consumer equipment.

gary wrote:They both look like bipolar steppers to me. There is a vague chance that the last one is a servo but I doubt it on the basis that they are almost unheard of in consumer equipment.

Hi Gary

I can not recall where i scrapped these motors from but i do know now and again i scrap something i have never seen before sounds like they are rare .

They both have normal Dc connections then the 2 extra hook these to a scope as the dc is running i get Ac out of the other two they look very useful i never bothered with them till now testing them...if its showing 400 hz that would mean its running at 750 rpm i suppose thats pretty interesting .


Heres my quick knock up generator getting some nice khz from direct drive perhaps a pulley system or diode frequency multiplier circuit might come in useful now .
I think the voltage is dropping as the frequency is rising .

Sorry Harry what do you mean by "normal Dc connections"?

gary wrote:Sorry Harry what do you mean by "normal Dc connections"?

I am doing 2 things at the same time talking about 2 different motors types and experiments .

Sorry .

The round back of stepper on my picture post above is the generator in that last post .

The black DC and long silver dc motors are a different test ...well i tested the black one showing 1 khz AC .

Both of these different motors have 4 wires 2 are like a DC motor hook them up to a DC supply and its just like a DC motor ...hook the extra 2 wires up to a scope and AC is coming out as the motor rotates ... very interesting !

I had it on 5 volts at the start and it was 380 or so HZ coming out of those extra connections

That certainly is interesting - are there any close ups of the 4 wire motors? Certainly if they were steppers you would NOT be able to run them off DC.

I would say then that they are DC motors with encoders attached - a neat score! I have about 100 or more scavenged motors and only one of them so well done.

gary wrote:That certainly is interesting - are there any close ups of the 4 wire motors? Certainly if they were steppers you would NOT be able to run them off DC.

I would say then that they are DC motors with encoders attached - a neat score! I have about 100 or more scavenged motors and only one of them so well done.

Yes Gary for sure they are not steppers ...they are Dc motor Ac generator in one !

What the hell are they ? but i wish they were all like that !

I just put every thing away for the night but i will take some better snaps tomorrow for you the Black one looks a little different to any thing else i have seen ....i wish i wondered what they were earlier little did i know .

I think the ones you have can be found in some old VCRs the encoder feeds into a speed controller for the motor. These have hall effect or similar sensors instead of opto sensors.

gary wrote:I think the ones you have can be found in some old VCRs the encoder feeds into a speed controller for the motor. These have hall effect or similar sensors instead of opto sensors.

Well i have scrapped many a vintage VCR so perhaps... last big ones were 2 top loading Beta vcrs .

Heres some pictures of the 2 DC motors with AC output.

Also i have 2 of these motors i think are bipolar steppers >? it seems to look like it could do some heavy work they are out of a giant of a laser printer i scrapped a year ago .

Yikes! Sorry Harry but I am lost as to which motor is which - could you add something to the photo description? Anyway I'll do my best:

P1050300) I have one of those COPAL motors that looks pretty much identical - and it is a bipolar stepper.

P1050303) I have never seen anything like that motor but the position of the wires seems to indicate it may be a DC motor with an encoder on the back. (or vice versa).

P1050304) To me that looks like a brushless DC motor - a synchronous motor if you like. The electronics around it would be required to use it. OTOH since it has 4 connections it could be a bipolar or a DC motor with encoder.

gary wrote:Yikes! Sorry Harry but I am lost as to which motor is which - could you add something to the photo description? Anyway I'll do my best:

Hi Gary sorry about that i found that big stepper motor last 2 pictures i wanted to see if you had seen one of those .

P1050300) I have one of those COPAL motors that looks pretty much identical - and it is a bipolar stepper.

I don't think its a stepper motor it says DC motor on the sticker has a red and black wires for the DC part and runs off DC ?

P1050303) I have never seen anything like that motor but the position of the wires seems to indicate it may be a DC motor with an encoder on the back. (or vice versa).

The red and blue wires are the DC part of it the AC comes out the yellow green wires same results as the copal motor as it runs when connected to DC AC is generated comes out the spare wires...
Really same type of motors results wise.

P1050304) To me that looks like a brushless DC motor - a synchronous motor if you like. The electronics around it would be required to use it. OTOH since it has 4 connections it could be a bipolar or a DC motor with encoder.

[/quote]

Yes it reminds me of a large pc fan motor where the magnet looks to be rotating ..i was looking at the 4 wires thinking it was a stepper i should look to see if it out puts AC or DC when turned might help.

Well i made this diode frequency doubler from this circuit .

Nice results big drop in voltage from input to output but inputs 13 volts Ac
at the doubled frequency of 9 KHZ it has dropped to bit over 4 volts those 470 ohm resistors might be worth a try using higher value resistor and or the cap value .
I suppose its a trade off .