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Author Topic: New DCC Autofrog  (Read 6868 times)

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Online dannyboy

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New DCC Autofrog
« on: July 07, 2016, 05:48:12 PM »
This may be of interest to some of you - 'Gaugemaster' have an autofrog available, ref. DCC80;

 :beers:
David.
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Offline Griffo

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Re: New DCC Autofrog
« Reply #1 on: July 07, 2016, 07:40:51 PM »

Online kirky

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Re: New DCC Autofrog
« Reply #2 on: July 07, 2016, 07:59:06 PM »
That looks as if it does the same thing as a Hex frog juicer. I've had some success with frog juicers, and some failures. But the gaugemaster one looks like it's nearly half the price. I'll be trying some.
Cheers
Kirky
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Offline njee20

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Re: New DCC Autofrog
« Reply #3 on: July 07, 2016, 08:19:42 PM »
I thought they looked interesting. Was tempted to try a few next time I'm down at Gaugemaster. Price isn't too bad, be nice if they did a bigger quantity rate.

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Re: New DCC Autofrog
« Reply #4 on: July 07, 2016, 08:29:05 PM »
be nice if they did a bigger quantity rate.

Get in there and ask - worst they can do is say "No".
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Offline njee20

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Re: New DCC Autofrog
« Reply #5 on: July 07, 2016, 08:47:03 PM »
Yep, very true. I imagine the margins are monstrous, but can't find the same thing on AliExpress!

I did once ask them to price match Rails/Hattons, they didnt, but did discount to be fair, so they can be amenable.

Offline Caz

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Re: New DCC Autofrog
« Reply #6 on: July 08, 2016, 12:41:07 PM »
That looks as if it does the same thing as a Hex frog juicer. I've had some success with frog juicers, and some failures. But the gaugemaster one looks like it's nearly half the price. I'll be trying some.
Cheers
Kirky

I think it could be half the price because it looks like it is using old technology, just a relay to switch the frog, the Hex Frog Juicer is all electronic, much more reliable.  I initially used the Digitrax AR1 modules on Claywell for reverse loops but they are just not reliable enough and now use a couple of the HFJ outputs to do the same job.

Online kirky

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Re: New DCC Autofrog
« Reply #7 on: July 08, 2016, 05:30:16 PM »
I think it could be half the price because it looks like it is using old technology, just a relay to switch the frog, the Hex Frog Juicer is all electronic, much more reliable.  I initially used the Digitrax AR1 modules on Claywell for reverse loops but they are just not reliable enough and now use a couple of the HFJ outputs to do the same job.
Ah, very interesting indeed. If it is just a relay, how does the device detect that the frog might not be switched in the same way as the blades are pointing?

Cheers
Kirky
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Online Railwaygun

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Re: New DCC Autofrog
« Reply #8 on: July 08, 2016, 09:20:54 PM »



The white device doesn't look much like a relay to me, and has a Do not recycle sticker! NUclear perhaps??
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Re: New DCC Autofrog
« Reply #9 on: July 09, 2016, 06:55:35 AM »
The Sticker means that it should be recycled and not just dropped in a bin .

Offline André-NL

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Re: New DCC Autofrog
« Reply #10 on: July 09, 2016, 12:29:25 PM »
Hi,

I think they put that sticker on so that we can't see it is normal latching relay  :D.

Gaugemaster was so kind to show the design of the Auto Frog circuit board in the manual  ;).


Managed this morning to make a diagram and solder some parts together.
Was really curious how they did it and i think this is the correct diagram.


These are the parts i used.
R1+R2 = Resistor 100 Ω 10 Ω
C1+C2 = Electrolytic capacitor 100 µf/25v
D1+D2 = Diode 1N4001
Relay    = Latching relay 12v
*          = I'm not shure but probably a resistor to lower the voltage on the relay (i didn't use one).

And it works  :claphappy:.
I was surprised a small circuit like this could do the job.

When one of the wheels drives on the frog you might think it makes a short circuit and switches of the dcc power.
But this is not really true because the 100 Ω 10 Ω resistor prevents that.
The current flowing to the frog always goes through the resistor so there might be a small voltage drop.

But when you start using a circuit board like this to switch the polarity of the frog you can also use a relay coupled to the pointmotor  :).
Just use the power to operate the pointmotor for the relay too.
That way you dont have to use that lovely DCC voltage to power relays etc.

André
« Last Edit: July 10, 2016, 07:39:47 PM by André-NL, Reason: Corrected the wrong resistor value »

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Re: New DCC Autofrog
« Reply #11 on: July 10, 2016, 10:32:53 AM »
Nice bit of backward engineering there Andre.   :thumbsup:

Offline Nigel Cliffe

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Re: New DCC Autofrog
« Reply #12 on: July 10, 2016, 11:32:29 AM »

Elsewhere on the MERG forum, there are suggestions that the above reverse-engineering has a few mistakes in it. 


-  Nigel

Offline André-NL

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Re: New DCC Autofrog
« Reply #13 on: July 10, 2016, 12:40:02 PM »
Nice bit of backward engineering there Andre.   :thumbsup:
Thanks, i hope it looks a bit like the original circuit.
Only used the photo and the circuitboard layout.


Elsewhere on the MERG forum, there are suggestions that the above reverse-engineering has a few mistakes in it. 


-  Nigel
Don't know if i made some mistakes or that there's something wrong with the original :).
But it does work. If the frog feed wire is connected to one of the rails the relay switches.
When the wire is connected to the other rail the relay switches to the other side. 

What suggestions do they give on the Merg forum?

I think there are a few,
The current to the frog always runs through a 100 Ω 10 Ω resistor so there's always a lower voltage on the frog.
If the dcc voltage is 15 volt, this design can only deliver 150mA to the frog and not 2 amps like they say in the manual.
The relay itself is capable of switching 2 amps.


And this design always consumes a little dcc power.

André


« Last Edit: July 10, 2016, 07:43:17 PM by André-NL, Reason: Made some corrections regarding resistor value »

Offline Nigel Cliffe

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Re: New DCC Autofrog
« Reply #14 on: July 10, 2016, 02:50:50 PM »


Elsewhere on the MERG forum, there are suggestions that the above reverse-engineering has a few mistakes in it. 


-  Nigel
Don't know if i made some mistakes or that there's something wrong with the original :).
But it does work. If the frog feed wire is connected to one of the rails the relay switches.
When the wire is connected to the other rail the relay switches to the other side. 

What suggestions do they give on the Merg forum?

I think there are a few,
The current to the frog always runs through a 100 Ω resistor so there's always a lower voltage on the frog.
If the dcc voltage is 15 volt, this design can only deliver 150mA to the frog and not 2 amps like they say in the manual.
The relay itself is capable of switching 2 amps.



It would be better if you looked at the MERG comments directly.   Essentially, they question whether the resistors are 100ohm, suggesting 10ohm instead.

They also comment that if there is 100ohm, then the device is useless because of the lack of current (or voltage under load) at the frog.   
If one uses 100ohm, and assume the loco/decoder is very efficient and drawing only 50mA, then the voltage drop over the resistor will be approx V=IR = 0.05X100 =5v, so the loco experiences as 5v drop in track voltage, so around 8 to 10v seen by the loco+decoder.  8v is marginal for operating many decoders, and a loco will experience a significant drop in speed. 
If the loco/decoder draw 100mA (common in N), then the voltage drop is 10v, and the loco sees only 3 to 5v, which is insufficient to run a decoder in any circumstances.  The frog is effectively a dead-frog. 

With 10ohm things are not so dire in terms of voltage drops. 


That the relay will switch on a short circuit is not an issue, it is whether the loco on the frog can gain any useful power. 


But, it would be better to pursue this on the MERG forums. 

-  Nigel

 

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