Selectable Voltage Sensing relay 0-18V AC

[marconi]

Cedar Falls, Iowa. North eastern portion of the state. I’m not too worried yet.

I will look this up in my world atlas

 

[marconi]

Cedar Falls, Iowa. North eastern portion of the state. I’m not too worried yet.

I live in London on its East side on the North side of the River Thames.

 

[jensenjosht]

Thank you. I will study what you have sent me. I think - cannot be sure just now - that the Lionel CW80 outputs a waveform as in my electrical art below to drive an ac universal motor. Forward and reverse is achieved by full wave rectification of the chopped sine wave (CSW) and then applying this waveform to the track with normal or swapped polarity - the second and third green waveforms. The frequency and peak voltage never changes. Speed control is by varying the delay before the sine wave is applied to the output the delay T being controlled by the throttle position. I do not know yet if the frequency of the output waveform is the same as the mains input sine wave which in the USA is 60Hertz. A variac on the mains input side may be a solution because it might reduce the amplitude of the output sine wave. A variac may not work though if the Lionel CW80 has voltage regulation on the output. Do you have a variac, an ac voltmeter and a couple of low wattage 12V filament lamps (not LED lamps)?

I have to ask in order to guide how I write to you - what is your level of understanding of electrical science please?

I have some bulbs that are 12v. I need to purchase a variac.

 

[jensenjosht]

Here is a simple diagram for the test. The single 24V lamp (or two similar 12V lamps in series) are connected to the traction terminals. Plug the Lionel(L) into the Variac (V) and ensure the Variac is set to output 120V. Now plug the Variac into the mains. The lamp(s) should illuminate.

Now reduce the Variac output voltage by a small amount and you should see the lamp(s) dim. If you reduce the Variac voltage by too much the Lionel will shut down because its internal 5V dc voltage regulator will turn off which in turn will turn off the electronics.

There is only a limited range over which you will be able to reduce the traction peak voltage. The Lionel's internal transformer outputs about 20Vac which after rectification is about 18Vdc. The minimum voltage at the input to the linear 5V dc voltage regulator is 7.2V - it is an LM78L05 if that means anything to you.. So if you use the Variac to reduce the 120V it will pro rata reduce the 20Vac and thence the 18Vdc until 7.2Vdc is reached and the Lionel will shut down. I do not advise you make such a large reduction. You will not need a big reduction to set an upper limit on the train's speed along the track because the power of the loco motor is roughly a function of the voltage squared.

Once we have demonstrated the V-L combination does indeed dim the lamp(s) we can move on to providing power to the locomotive.

PS: The maximum current from the Lionel is about 5A so the total wattage of the lamp(s) must less than 5 x 18 = 90W.

Looks good but it might be a bit. I’ve got to get a varriac.

 

[marconi]

Looks good but it might be a bit. I’ve got to get a varriac.

Do ask me for further explanations if you are not sure about something.

 

[jensenjosht]

Do ask me for further explanations if you are not sure about something.

Like I meant that I need to physically acquire one. Just placed an order for one, a week from now.

 

[marconi]

Thank you. Please would you send me a link to or details of the variac you have ordered.

 

[jensenjosht]

Thank you. Please would you send me a link to or details of the variac you have ordered.

 

[jensenjosht]

Thank you. Please would you send me a link to or details of the variac you have ordered.

I just ran the experiments and even a few with various locomotives and I’m fairly impressed with results. I had to dial in the voltage on a few engines depending how they ran but overall impressed. One thing to note is that engines that use a classic air/tender(Polar Express for me) need to be dialed in at the right voltage otherwise they won’t sing as well or at all. Since you’re a London man, thought you might enjoy this. Pardon the mess. It’s not easy when you have a small apartment to play trains in.

 

[marconi]

I am pleased to here your original idea has worked. I think forum members would like to see the model railway if you would not mind posting a picture.

PS: Un plug or switch off the variac when not in use because even when there is nothing plugged into it there will be a small power consumption.

PS2: I suggest you buy a few more of the fuses which arrived with the variac, the exact same ones, because occasionally they can rupture due to what is called the switch on surge current. They should be marked up with their details.

 

[jensenjosht]

I am pleased to here your original idea has worked. I think forum members would like to see the model railway if you would not mind posting a picture.

PS: Un plug or switch off the variac when not in use because even when there is nothing plugged into it there will be a small power consumption.

PS2: I suggest you buy a few more of the fuses which arrived with the variac, the exact same ones, because occasionally they can rupture due to what is called the switch on surge current. They should be marked up with their details.

Sounds good. The event date is 11/17 I might be able to get some pics of the layout to you earlier. I’m sure the forum members will be pleased to see it.