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[msun2000]

Hi,

Has anyone succeed in modifying PH508 power siren to act as a
relay as described in the following URL?
http://www.pigselectronics.com/tektips/tip3.htm

I tried it and was not able to trigger my 5V microrelay, the voltage
change on the diode when alarm went off was 2V.

Thanks,
Michael

[Brian H]

I tried it and will check my notes. I made many measurements. My problem was finding a relay that matched the hole pattern and signal pinout. My Radio Shack one physically fit but the signals where NOT on the correct pins. 

[Brian H]

OK my unofficial tests and findings:
The PH508 has three power supplies in it all with a common connection. +28 volts; -28 volts and -15 volts. The -15 is from a 79L15 off the -28 volts.
+28 to the one end of R30. R30 to relay coil and bar end of diode D16. Other end relay coil to collector TR8. TR8 Emitter to -15 volts. So when TR8 turns on the relay is connected to +28 and -15. The -15 is a very low current regulator so if you check your relays current rating my guess it is way over 100ma that the regulator can provide and that does not include the load already on it from the other circuits.
I personally was trying a sensitive coil type relay in my tests. I think it was a 24 volt one with a few thousand ohm coil. Only needed like 10 ma to trip. Also since R30 is what drops the extra voltage. It also may have to be selected and wattage maybe greater depending on your conditions.
I also used a different TR8 as the 2N2222 has a rating of 60 volts if memory serves me. I used a 100 volt only for greater margin of reliability, but the 2N2222 is probably fine.
I can check my parts bin if you want more details

[msun2000]

I have the following in place:

R30 - 1Kohm 1/2W RadioShack 271-1118
R32 - 12Kohm 1/4W NTE QW312
R33 - 12Kohm 1/4W NTE QW312
R34 - 200Kohm 1/4W NTE QW420
R35 - 200Kohm 1/4W NTE QW420
D16 - RadioShack 276-1102 diode 200V 1A
TR8 - RadioShack 276-1617 NPN-Type
RL1 - RadioShack 275-240 SPDT Micromini relay 5VDC
        Coil voltage nominal: 5VDC
        Coil voltage maximum: 6.5VDC
        Nominal current: 89.3mA
        Pick-up voltage: 3.5VDC
        Drop-out voltage: 0.25VDC
        Coil resistance: 56ohms +- 10%

I have re-route the pin on the relay so the coil is now connected to the diode,
if I measure 2V on R30, would replacing R30 to 1Kohm 1W bump the voltage
on the relay coil to 5V?

[Dan Lawrence]

Pigs Electronics give these "tech tips" to use at your own convience only.  The owner (An X10 Dealer in the Baltimore, MD area) gives no assurances they will work.

The site, BTW is on a Baltimore server.

I deal with the site/owner quite often.

[Brian H]

89.3 ma is a heavy extra load on the -15 Volt regulator; but it may work. No the wattage being higher will just allow it to run cooler. A lower resistance would allow more current to flow and the voltage across the relay coil would be higher. Then you may need a 1 watt to not get too hot.
Like Dan said Pigs mods are at your own risk. Then again my test PH508 is expendable as X10 had a buy one get 3 free deal when I got mine.
Just like the mods on other forums. Like I modified some LM465 modules with a Sharp SSR for a quiet module that can do inductive loads like small motors.

[Brian H]

Ok rough calculations as the supply voltages may load down further as the current goes up.
Try a 680 Ohm then a 560 Ohm then a 470 Ohm all 1 watt to be safer. From the highest value down to get the lowest current to work properly.
Better shot maybe the Radio Shack 12 volt version of the 5 volt one you tried as it needs less current to pull in and has a higher resistance. In that case the 1000 Ohm R30 maybe OK.
Remember it is possible to damage the PH508
Tried the Radio Shack 275-0241 12 Volt version in the circuit. I get about 9.6 Volts on the relay coil. It did pick up and I think Gary at pigs may have under rated the R30. Mine got fairly hot. The R30 maybe lowered to maybe 820 Ohms to raise the voltage on the 12 version. Maybe a squeezed in 1 watt also. Though some of the newer type resistors are smaller per watt than composition ones like I used for R30.

[msun2000]

Okay I haven't got the other resistors yet but I just found out the relay switch was working when I was trying to measure the current over R30.

When alarm triggers, R30 (1K ohm 1/2W) shows 2VDC and 150mA, so if the spec on the relay switch is 5VDC 89mA in theory I need a
5/0.089=56 ohm resistor on R30, but since the relay switch already has 56 ohm coil resistance, is it safe for me to just hard wire the two pins for R30?

Please bear with me because I don't have too much EE knowledge...

[Brian H]

No the supply voltage is the +28 [small load seems to drop when siren triggers]on one end and -15 on the other. X10 used a bipolar supply. Total is about 37 volts [triggered]. So the total resistance has to be the coils added to the R30 value. The calculations maybe messed up in your 5 volt coil as the -15 volt supply can only do 100 ma due to the low power regulators shutting down.
In my case the 12 volt relay and the 1000 Ohm R30 get me about 9.5 volts on the relay.
If you jump R30 it will probably smoke the relay and maybe the PH508 power supply.

I think that the modification instructions should have given better details on selecting a relay.
With your 5 volt; 56 Ohm coil ;.089A [89ma]. The R30 value would have to be around 400 Ohms at 3.5 Watts. Also the 89ma extra load on the supplies may overtax them.
The 12 volt version of the relay with a 320 Ohm coil .037A [37ma] needs about a 680 Ohm 1 watt resistor.
That is why I was looking at 24 volt coil relays as they required less current to activate and the power rating of R30 could be lowered and its value raised.

[msun2000]

I replaced R30 with a 470 ohm 2watt resistor and it worked with the 5V relay, when alarm triggers the relay coil voltage shows 3.6 - 3.7 VDC, just barely make the pick-up voltage.

[Brian H]

Glad it works. Personally I would worry about overloading the power supply. The relay in the modification data should have been called out better.
I tested with a RS 275-233 12V reed relay that has a coil of 1050 Ohms and needed 11ma. With that setup the supply voltage dropped less and the R30 value was 2200 Ohm and could have been a 2700 Ohm one. 1/2 watt didn't even get warm.
Too bad X10 didn't include the relay output. As all the bare PC artwork area is there to add it.

[msun2000]

I also found another document to modify the PH508 as relay using different components but sorry I couldn't remember where I got it from (google), but anyway here it is:

############################################################

ALTERNATE VERSION:
===================

One of the great shortcomings of the X-10 wireless security system is the lack of an interface to external devices, like a strobe and/or siren, to alert neighbors of a burglary or other emergency situation.  The following modification adds that capability.

When an alarm is activated, the base (receiving) unit wails its siren and sends out alternately, at about one second intervals, the signals ALL LIGHTS ON, ALL UNITS OFF.  This has the effect of flashing all lights on the same house code.  You can buy a remote, plug-in power siren which has been designed to trigger when it receives 4-5 on-off cycles, alternating its two-tone horn in synch with the ON-OFF signals.  However, it is not suitable for outdoor installation.

As noted by others, the power siren circuit board contains space for an optional external relay interface circuit, although units with this option seem never to have been produced.  It would provide a low-voltage contact closure (30VAC, 2A max.).

In this note I will describe how to make the modification, based on schematics from X-10 engineering and my own testing.  This improves upon earlier recommendations in the X-10 FAQ.

Modification:

Install the following components in their marked location on the circuit board:

    R30      470 ohm 2 watts     do not allow to touch other components
    R31      2.7 K   1/2 watt    just fits: do not substitute or leave out
    R32      2.7 K   1/4 watt
    R33      100 K   1/4 watt
    R34      100 K   1/4 watt
    R35      150 K   1/4 watt
    R36      1 K     1/4 watt
    C18      10 uf   16 volts    + on board is marked with a diamond
    D16      1N4001  1 AMP diode
    TR8      TEC9014 (almost any 100ma NPN switching transistor will work)
    RL1      5 volt, 72 ma DIP relay, Radio Shack #275-243

Remove R8 (or just clip the leads).  There may be a resistor in parallel with R8, remove it also.  This was used to keep the unregulated and unloaded + supply from floating up too high, and is now taken care of by R31.

Activated (and unmodified), the unit consumes about 70ma, powered on the - side by a 100ma regulator.  The relay modification consumes an additional 70 ma, over-taxing the power supply and regulator.  Even though it will still work for a brief time when activated, you risk having the regulator shut-down or the transformer overheat.  To get reliable operation within safe-area limits, change the wiring to the piezo elements.  The unit comes from the factory in which all four elements are wired in parallel.  Change the wiring so that they are in a series-parallel configuration, reducing their current drain from 50ma to 12.5ma, and reducing their total sound level from 105db to 99db.

Code: [Select]

             --| |--    --| |--
          __/       \__/       \__      (piezo element wiring change)
            \       /  \       /
             --| |--    --| |--

You should maintain consistent polarity when rewiring the elements, and if you are clever, you can do it by removing one brown wire at the top, switch the polarity of the other brown wire at the top, and use the wire you removed to relocate and extend the blue wire to the opposite side (cover the exposed connection).  Since you are going to hook up an external siren presumably, the loss of indoor volume should not pose a problem (I think it's too loud anyway).

Finally, you need to install screw terminals in the slots provided.  I used terminals taken from an X-10 door/window sensor in which I permanently soldered the wires connecting to the magnet.  Before installing them, you must break off the side tabs which are on top and next to the screw, otherwise the rear cover of the case won't fit.  They don't quite stick up as high as I'd like, so if anyone has a better source of screw terminals I'd like to know.  Now, remove the adhesive cover plate on the rear cover, and write in red marker next to the terminals "30 volts, 2 amp max."
############################################################

So from the docs it looks like a safer mod but it'd be interesting if someone can verify this 

[Brian H]

OK the added resistors in like R31 maybe the missing key. Thanks for posting the updated information.

[dave w]

A little off topic, but I see a lot of PH508 expertise here.

Is there anyway to get the PH508 to "lock on" until the appropriate OFF code is sent, like the small power horn SH10A will do?

Thanks!

Dave

[Brian H]

Not that I have seen, but I have seen the SH10A lock on [actually it will timeout in 4 minutes by my tests]; by sending a stream of Ons to it.