Railfan Technology > Power Supply & activators for Block Signals

Not sure what forum to post this but will give it a try here.  I'm looking for an ex-signalman or a knowledgable electronic guru here.  I once heard of a person who wanted to operate a block signal in his driveway, alerting him when a delivery truck arrived , so I was wondering what type power supply would be needed to (1) activate a US&S H-5 searchlight signal lamp and to power the 3-color internal unit and for (2) a three-color tri-light such as once used by the Rock Island RR.
The stock lamps that came with the H-5 searchlight signal are 10v 25w and I think 10v 14w for the RI signal.  I'd prefer to use the original lamps that are intact, but know the tri-color could use an automotive 12v bayonet base lamp like an older model tail light lamp but I don't think the filimant location for the fresnels of the lens would be corectly located.  I'm unsure what it takes to power the H-5 internal color mechanism.  So far, I've researched online and have found mostly 12v power supply units.  Im not sure about the amperages to use and if this would work with either of the 10v lamps.  Also, I'd like suggestions for activation, such as, motion detectors for activating and for changing the colors.  Having said this, I'd like to keep the cost to a minimum.  Any help is appreciated!                                                                                                                                



Edited 2 time(s). Last edit at 09/22/16 12:37 by rrman6.

The 10v25w lamp will draw 2.5 amps, the 14w lamps will draw 1.4 amps each. The H5 will not draw more than an .5 amps, so an automotive 6amp battery charger will handle it just fine.
An infrared motion detector with a 12v time relay will do the trick.



Edited 1 time(s). Last edit at 09/22/16 16:01 by SP4360.

SP4360 Wrote:
-------------------------------------------------------
> The 10v25w lamp will draw 2.5 amps, the 14w lamps
> will draw 1.4 amps each. The H5 will not draw more
> than an .5 amps, so an automotive 6amp battery
> charger will handle it just fine.
> An infrared motion detector with a 12v time relay
> will do the trick.

As a signal maintainer on the old SP Tucumcari GS line, I trust your knowledge here and appreciate much your assistance.  I will research further for the motion detector w/ 12v time relay.  If you have a suggestion on this item I'd welcome that also.  Thanks and have a great evening!!



Edited 1 time(s). Last edit at 09/22/16 18:44 by rrman6.

Automotive battery chargers are typically not regulated.  The "open circuit"  voltage may exceed 16 volts. 
A small load such as the lamps in the signal may not be sufficient to draw the voltage down to a suitable operating level.

For the same reason, I'd avoid "wall-wart" power supplies.

Some things you may wish to try:

Use a model train power supply and set the  output to @10 volts under load.  Make certain the power supply has a proper
current rating. 

Connect the outputs of a pair of 5V internal computer power supplies in series to get 10 volts out (regulated.)
Watch the connections! Some of these have truly weird output voltage sensing circuits. 

As for the sensor, I'd go with a "motion sensor" floodlight fixture with the light sensor taped over with black electrical
tape so the sensor thinks it is "night" all the time.  These devices most often have an adjustable "stay on" period.  Use the
output of the sensor to provide mains current for the power supply.

Harbor Freight sells a driveway alert system (#93068) which has a battery powered sensor and a battery backup,
wall-wart primary chime.  I've used these and they are really not awful.  You would have to contrive some manner of on
time adjustable "one shot" triggered by the chime to control the block lights.

Sources:

BG Micro
All Electronics
Electronic Goldmine
Marlin P Jones

Be Well,

Tim Colbert  K3HX



Edited 1 time(s). Last edit at 09/23/16 11:24 by K3HX.

Thanks Tim.  I'm not an electronic guru but your information here is helpful and later this season when time allows I will hopefully attempt some experimentation.  From what I see these computer power supplies are affordable if salvaged ones aren't available.  Thanks and best wishes for your weekend!

I use wall warts on my layout for  LED power all the time, no open load run away voltage. They are regulated for electronic devices. Never hd a problem with small automtive battery cahergers either. The newer ones need a small, such as a battery for an alarm system or exit sign. You can find adjustable timers on Ebay cheap. I use them for time delay on my tortoise switch machines and other circuits. They are small, 12 volt and can be adjusted from a few seconds to minutes depending on the one purchased.

SP4360:

Kind sir, you have been misinformed.

"Wall-warts"  are typically not voltage regulated.  The ones that are regulated
mostly use a switching regulator.  I would be grateful to know of one that
has a regulated output of 10 volts DC with a capacity of 2.5 amps
(2500 "mils") to provide power for the incadescent lamp in the signal.

Using "wall-warts" to power LED lamps on a model layout is another matter.
Typical operating current for a LED is  @20 "mils"  (20 thousandths  of an ampere)
at around 3 to about 4.5 volts depending on the structure of the LED.  Perhaps
you are using LED  with a ballast resistor to permit operation with a higher
supply voltage or a special variant with a regulator built into the LED.

Using a switcher-regulated "wall-wart" on a model layout can be a problem if you
choose to use the rails or radio to communicate commands. 
Switching regulators, especially ones in cheap power supplies are notorious for
causing electrical noise which can interfere with the operation of the layout. 
You may be able to hear the racket by holding a portable AM broadcast radio
near the "wall-wart."

Automobile battery chargers are not regulated in the sense that power supplies
are regulated.  Most are current-limited so they don't "cook" the battery (overcharge)
or self-ignite.  The circuitry in the more modern auto battery chargers operates on a
profile to bring the battery up to full charge and hold ("float") the battery in a
fully charged state.  For this to happen, the voltage output from the charger
must be greater than the battery.  Normal "open circuit" voltage can be as high
as 16 volts DC.  Even in "float" mode the voltage applied may be over 13 volts.

This voltage will cause premature incadenscent bulb failure for a bulb rated at 10 volts.

Be Well,

Tim Colbert  K3HX


 



Edited 1 time(s). Last edit at 09/28/16 15:23 by K3HX.