I am using a RP1 on a new project. I am loooking for a transformer to use for the power sensing for the cable box.

The specs on the RP1 say that it has to be 3-12 VDC.

I had a previous post in regard to the power sensing module and the RP6 and that I had used a 12v DC adapter and it took to long to discharge so the system would still show that the power was on even though the box was off, if you powered the system right back on. The solution was to use a 12V AC 100ma transformer since the AC will discharge much faster.

If this is the case I would like to source a DC transformer that is closer to the 3-4VDC so that it should pretty much discharge enough one the component is turned off. (RP1 says that 2VDC or less indicate an off state).

Does anyone have a source.

I did find the following online:

5.5VDC
[Link: allelectronics.com]

3VDC
[Link: allelectronics.com]

I didn't know the RP1 can sense power. I thought it was only on RP6 w/power or voltage sensing modules.

The manual states the off voltage is 0-2vdc and the on is 3-20vdc

just use a 12v wall wart around 300mv and you should be fine, or a 9 or 6 v will be fine too, I think if you drop down to close to the 3v you might get marginal results

I havent had any issues using 12v triggers into the RP-1, I usually use them on cable boxes...plugged into the switched outlet

Just place the system test close to the front of the macro and it should power down by the end of the macro

I use a Xantech 781RG all the time. Takes about 3 seconds to fully discharge.

BenfordAV:

Ues, there's a port on the connecting block. Actually works better than the RP6, becaise you don't need the adapter module.

Can also use a video sensor in the power sense port on the RP-1

I havent done one but can be done easily

Sweet, good to know, I guess it's only one port/source of course.

Recently had this issue while walking thru with new client/system. I discovered that the real lag time was the cable/dvr (SA 8300HD) not switching off the outlet immediately. There was about a 20-30 second delay from shut down to an audible click inside the dvr, during which it sounded like the harddrive (maybe fan) was still running. Then it would sync fine.

estech's note is a complete surprise. That one's worth looking for if there's a problem!

This is a great answer. Regulated supplies have circuitry inside it that drains the storage capacitors pretty rapidly so the voltage falls in a few seconds.

For garden variety cheapo supplies, the answer is to put a load on the transformer. A 1000 ohm resistor from plus to minus will drop that voltage very rapidly an not otherwise affect how it works. A larger resistor will take longer, and smaller resistor will draw more current and may make the voltage sag or make the resistor get hot.
I sometimes put a resistor and an LED on it, which then also gives me a visual indication that the supply is on. All of this complicates things because then wires are exposed. A small terminal strip from Radio Shack, especially the translucent white plastic ones with insulated screws, work great to minimize wire exposure.

Also note that when a supply takes a long time to discharge, that shows that it's in a circuit where very little current is being drawn from it. If the supply is not regulated, its voltage is higher than the rated voltage. 12 volt supplies are usually 16 to 17 volts, 9 volt supplies around 12 volts, in this circumstance.

Run that by me again? A video sensor? Isn't that made to plug into the RP6?

Yes but can be modified to be used on an RP-1, hers a tech bulletin on the RTI site

cut the plug off and strip back the jacket and use 3 wires...power, Ground and sense

the tech bulletin even says what wires go where

***edit: link to tech bulletin

[Link: rticorp.com]

I've spec'd to do this on a current job, as setting the 3250 to power-on via "number" resets itself if cocast does a hard reset. It really isn't that much more expensive, and you don't have to worry about which transformer to use.

I alweays like to be aware of tidbits like this.

A 3250 what?

What is cocast?

Sorry, Comcast. I was holding a baby when I typed it.

The SA3250HD from Time Warner, and some Comcast boxes. We switched from TW to Comcast a little over a year ago, and most people still have the TW software boxes.

For most of the S.A. boxes, even most of the new ones we have been seeing from Comcast, have a feature that will power on by pressing a numeric key or the power button.

Press the menu/settings button twice to get into the extended menu.
Under "Set: Power-On Keys" there is an option for "Power" and one for "Power on with numeric" I usually program my macros to as "0,0,Exit" to turn on the box, then put the "power" command in the power off macro.

Unfortunately, if Comcast does anything to the boxes, it usually reverts back to just the "power" feature in the menu, making the macro unusable.

Regarding the SA cable boxes, some cable companies choose the full menus and others do not. If the full menus are there this works nicely. But many will not find the full menus in their local cabel provider's boxes.

Dave