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Info needed but NOT too technical! - Electrics - DC - Getting You Started. - Your Model Railway Club
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 Posted: Tue Feb 19th, 2013 05:44 pm
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petercharlesfagg
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Friends,
This is the circuit tester that I purchased 20 years ago for setting up my first model railway and it did the job intended as regards electrical connectivity!


I also built my own transformer with (2) outlets for 16 V AC.


After I had built the transformer there was some speculation amongst the members of the Isle of Wight "N" gauge society as to whether the transformer was actually producing the current needed because the point motors were slow and the locomotive (Jinty) was slow in operation.


The components were supplied by a reputable company who recommended them as being compatible and trustworthy!


Therefore, can anyone instruct me, gently, as to how I can use the tester to test the outputs on the transformer?

  
PLEASE keep the technical jargon to a minimum
Regards Peter.



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 Posted: Tue Feb 19th, 2013 08:44 pm
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MaxSouthOz
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Hi Peter.  It looks like the AC Voltage range is at the bottom.

If you use the 50 Volt position, you should get a reading on your needle.



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 Posted: Wed Feb 20th, 2013 05:19 am
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petercharlesfagg
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MaxSouthOz wrote: Hi Peter.  It looks like the AC Voltage range is at the bottom.

If you use the 50 Volt position, you should get a reading on your needle.
Thankyou but what am I looking for on the scale and where?
Regards Peter.



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 Posted: Wed Feb 20th, 2013 05:43 am
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MaxSouthOz
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The second row of numbers reads 0 - 50, Peter.

The graduations for individual Volts is in red.



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 Posted: Wed Feb 20th, 2013 06:01 am
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petercharlesfagg
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MaxSouthOz wrote: The second row of numbers reads 0 - 50, Peter.

The graduations for individual Volts is in red.
Max, 
Thankyou.
Regards Peter.



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 Posted: Wed Feb 20th, 2013 07:02 am
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xdford
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Hello Peter

The circuit you have is called an Analog meter and relies on movement of the needle from 0 on the left and Full Scale Deflection on the right hand side for maximum voltage and current.  

The top line on your scale is the resistance line expressed in Ohms which is in reverse to the other scales but if you will, it is showing that a full electrical current will flow through  a wire. Before using this scale you should make sure that there is no power. You said you have used it for a continuity tester so I assume there is not much need to go much further than that except to say that you would be seeing a flow through your wiring when the Ohm meter scale is read...  

The small mirror which runs the length of the scale is so that you can align it visually and read exactly the voltage when you can only see one needle line instead of two through being out of parallax view.

The small screw head at the top is to adjust the Full Scale deflection to read zero when you just touch the two prods. You hold the two prods together then turn the screw till the meter does read right on the zero line which takes care of the life of the battery/ies inside the meter.
To check the voltage is easy. Firstly set your dial to the highest AC voltage (ACV) or DC Voltage(DCV) that you think you are likely to be using so as Max said 50 Volts. 

The next three scales reading down in order are 250V 50V and 10V.  Say the meter is showing the needle on 150 mark then depending on the scale on the selection dial, you are using you will have either 150V, 30 V or  6 volts. 

If it is reading 3 of the small markings beyond this marker, then you would be seeing  either 165V (because each small marker is on the scale equal to 5 volts), 33 V (because each small marker is on the scale then be equal to 1 volt) or  6.6 volts (because each small marker is on the scale equal to .2 volts) 

And just to be pedantic, If it is reading 2 of the small markings beyond the second marker, then you would be seeing  110V (because each small marker is on the scale equal to 5 volts), 22 V (because each small marker is on the scale then be equal to 1 volt)or  4.4 volts (because each small marker is on the scale equal to .2 volts) - I must admit that copy and paste makes it very easy to be pedantic!!!

If you are not sure what voltage is present, you should test the connection by setting your scale to the highest AC voltage before applying the probes.  If you apply the probes to a DC output, the voltage is rectified anyway. If your setting is too low say 12 or 14 volts and you have it on the 10 volt selection, the dial will race to the right but generally speaking, no harm will be done. just disconnect the probes or turn it off and reset to the higher voltage selection.

What you cannot tell very easily is what current the transformer is putting out. Very few transformers will put out enough for the sudden current flow that a point motor generates and you would do wise to have a Capacitor Discharge Unit to power your points. 

Are you referring to a Triang OO Jinty and if so what vintage or what type do you have? The older locos were notoriously heavy on power and your transformer may not be keeping up?

Perhaps a little more information from you and perhaps a bit of feedback as to how simple or complex this was for you, but hope this helps 

Regards from Melbourne

Trevor

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 Posted: Wed Feb 20th, 2013 03:42 pm
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gastwo
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Can I butt in and say thank you to Trevor?

I've learnt a little bit more today!

Shaun.

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 Posted: Wed Feb 20th, 2013 06:55 pm
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petercharlesfagg
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xdford wrote: Hello Peter

The circuit you have is called an Analog meter and relies on movement of the needle from 0 on the left and Full Scale Deflection on the right hand side for maximum voltage and current.  

The top line on your scale is the resistance line expressed in Ohms which is in reverse to the other scales but if you will, it is showing that a full electrical current will flow through  a wire. Before using this scale you should make sure that there is no power. You said you have used it for a continuity tester so I assume there is not much need to go much further than that except to say that you would be seeing a flow through your wiring when the Ohm meter scale is read...  

The small mirror which runs the length of the scale is so that you can align it visually and read exactly the voltage when you can only see one needle line instead of two through being out of parallax view.

The small screw head at the top is to adjust the Full Scale deflection to read zero when you just touch the two prods. You hold the two prods together then turn the screw till the meter does read right on the zero line which takes care of the life of the battery/ies inside the meter.
To check the voltage is easy. Firstly set your dial to the highest AC voltage (ACV) or DC Voltage(DCV) that you think you are likely to be using so as Max said 50 Volts. 

The next three scales reading down in order are 250V 50V and 10V.  Say the meter is showing the needle on 150 mark then depending on the scale on the selection dial, you are using you will have either 150V, 30 V or  6 volts. 

If it is reading 3 of the small markings beyond this marker, then you would be seeing  165V (because each small marker is on the scale equal to 5 volts), 33 V (because each small marker is on the scale then be equal to 1 volt)or  6.6 volts (because each small marker is on the scale equal to 5 volts), 33 V (because each small marker is on the scale then be equal to .2 volt)

And just to be pedantic, If it is reading 2 of the small markings beyond the second marker, then you would be seeing  110V (because each small marker is on the scale equal to 5 volts), 22 V (because each small marker is on the scale then be equal to 1 volt)or  4.4 volts (because each small marker is on the scale equal to 5 volts), 33 V (because each small marker is on the scale then be equal to .2 volt) - I must admit that copy and paste make s it very easy to be pedantic!!!

If you are not sure what voltage is present, you should test the connection by setting your scale to the highest AC voltage before applying the probes.  If you apply the probes to a DC output, the voltage is rectified anyway. If your setting is too low say 12 or 14 volts and you have it on the 10 volt selection, the dial will race to the right but generally speaking, no harm will be done. just disconnect the probes or turn it off and reset to the higher voltage selection.

What you cannot tell very easily is what current the transformer is putting out. Very few transformers will put out enough for the sudden current flow that a point motor generates and you would do wise to have a Capacitor Discharge Unit to power your points. 

Are you referring to a Triang OO Jinty and if so what vintage or what type do you have? The older locos were notoriously heavy on power and you transformer may not be keeping up?
Perhaps a little more information from you and perhaps a bit of feedback as to how simple or complex this was for you, but hope this helps 

Regards from Melbourne

Trevor
Well I never dreamed that someone would take the trouble to explain both simply and concise as to the use of my little circuit tester!

Trevor, you deserve a medal!


You wrote:- "You said you have used it for a continuity tester so I assume there is not much need to go much further than that except to say that you would be seeing a flow through your wiring when the Ohm meter scale is read...  "


Yes I only used it in the sense that the probes were connected to track or the domestic plug to test the connections, nothing more!


It is really good to have complicated matters explained thus because everyone can gain some knowledge as has been seen!


I will print off these details and when I have acquired a new locomotive and track I will put it into operation.


The "Jinty" I referred to was a GF N locomotive over 20 years ago so I feel certain that standards of manufacture have improved greatly!


]My grateful thanks, Peter.



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 Posted: Wed Feb 20th, 2013 09:40 pm
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xdford
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Thank you Shaun and you are welcome Peter.

Because I am a bit slippery when it comes to typing, a typo or two appeared on the original. I must hit a wrong key when copying and pasting so perhaps it is not so easy to be pedantic but I digress... the original has been edited

Peter, your transformer may well have been labelled say 18VA or 24VA or similar. a VA is a Volt times an Ampere so if your output is 12 volts, then 18VA would mean that you have 1.5 amps ready to power your train which should be more than adequate but of course I cannot see what you are actually powering with it. 16V AC would be producing 1.1 Amps at 18VA or 1.5 at 24VA and so it goes. The other variation of this is the Watt which is also a Volt multiplied by an Ampere. Using VA sounds more scientific and blinds the general public! 

Many years ago, we had a washing machine that when it started a cycle, the lights in the house would noticeably dim momentarily. If you have not got a capacitor discharge unit the effect on your trains and transformer would be the same in a smaller scake with current flow being drained by the point motor. 
I noticed you said you put two 16V AC connections on your transformer?  Nothing wrong with that in principle but what are they actually powering?  I suspect that there is something heavily draining on your system or a slight fault. 
 I have  protection resistors on my home made transistor throttles. Because I sometimes but seldom double head, I do not have a problem. Another modeller came  over and tried to run a quadruple loco (a bit embarrassing on a 4x8 but there you go...) but after 3 locos, the power supply just dropped off due to the protection I put in.  I wonder if you have done something similar?


Anyway, let me know!


Regards

Trevor

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 Posted: Wed Feb 20th, 2013 09:50 pm
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MaxSouthOz
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Sorry, Peter.  I wasn't being difficult.

I was trying to keep it simple.



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 Posted: Wed Feb 20th, 2013 11:15 pm
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SoundandDirty
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Well done Trevor,

excellent information

Kim

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 Posted: Thu Feb 21st, 2013 06:59 am
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petercharlesfagg
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xdford wrote: Thank you Shaun and you are welcome Peter.

Because I am a bit slippery when it comes to typing, a typo or two appeared on the original. I must hit a wrong key when copying and pasting so perhaps it is not so easy to be pedantic but I digress... the original has been edited

Peter, your transformer may well have been labelled say 18VA or 24VA or similar. a VA is a Volt times an Ampere so if your output is 12 volts, then 18VA would mean that you have 1.5 amps ready to power your train which should be more than adequate but of course I cannot see what you are actually powering with it. 16V AC would be producing 1.1 Amps at 18VA or 1.5 at 24VA and so it goes. The other variation of this is the Watt which is also a Volt multiplied by an Ampere. Using VA sounds more scientific and blinds the general public! 

Many years ago, we had a washing machine that when it started a cycle, the lights in the house would noticeably dim momentarily. If you have not got a capacitor discharge unit the effect on your trains and transformer would be the same in a smaller scake with current flow being drained by the point motor. 
I noticed you said you put two 16V AC connections on your transformer?  Nothing wrong with that in principle but what are they actually powering?  I suspect that there is something heavily draining on your system or a slight fault. 
 I have  protection resistors on my home made transistor throttles. Because I sometimes but seldom double head, I do not have a problem. Another modeller came  over and tried to run a quadruple loco (a bit embarrassing on a 4x8 but there you go...) but after 3 locos, the power supply just dropped off due to the protection I put in.  I wonder if you have done something similar?


Anyway, let me know!


Regards

Trevor
Trevor,It gets better and better!
The transformer I utilised was designed to power (2) 16 volt AC outlets, (1) was ascribed to only the controller and the other to the CDU. (Akin to the Gaugemaster M1)  

It was purchased from a VERY reliable source that model railway constructors have been using for more years that they would probably care to remember!

At this moment in time there is nothing upon which to test the transformer hence my wishing to use my circuit tester. (See 1st post)

Even with all yours and others help, I am beginning to think that it might be a VERY good idea to have the item tested by someone who knows the intricacies and vagaries of mains power transforming.
 
Again, I am overwhelmed by the response to this question and the answers will obviously benefit more than just myself!

Warmest regards Peter.



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 Posted: Thu Feb 21st, 2013 07:38 am
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xdford
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MaxSouthOz wrote: Sorry, Peter.  I wasn't being difficult.

I was trying to keep it simple.

Hi Max,

You were keeping it simple - and well done for trying to be concise/exact/both of the above!

Speaking foir myself, I do have to work almost overtime to make sure I am not doing the equivalent of teaching someone how to tell time by teaching them how to build a clock! If enough of us sent in small  and" to the point" points as you did, for the queries that do come up then, Peter and a few others could pick up the parts they need!

So perhaps more of a pool of input would work well! What happens is up to the other members of the group of course but I don't think you need to apologise...


Cheers and Regards

Trevor

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