LED Circuit?

[Drew]

I'm trying to apply a tally light system: a Panasonic video switcher
that sends a signal, and I want a couple of LEDs to turn on 150ft.
away whenever that signal is on. That's it.

Whether I'm building it myself or not, I need to understand what the
switcher does and doesn't handle, so I don't overload any of the
Panasonic's components - it's a $11,000 device. Here's the information
I have about its (D-sub15) control output:
http://www.drewlahat.com/misc/AV-HS400N_tally.GIF

Is it designed to drive LEDs directly, or would you recommend a relay?
What should also be in there to protect the unit (diodes)?

The signal has to go through 150 ft. of 26 AWG (7x34) Stranded TC
wire, rated at 38.5 ohm/Mft.

I might be able to use an off-the-shelf tally system - Datavideo TB5
(http://www.datavideo.us/products/TB_5_main_page.htm). Since it's
designed to connect to their own video switcher, there isn't much info
available. All I have is the Datavideo switcher diagram, which the TB5
is designed for:
http://www.drewlahat.com/misc/Datavideo_switcher_Tally_pinout.GIF

Given the right cable, should I be able to connect the TB5 to the
Panasonic directly and suppose everything will work fine, or not
necessarily?

 

[Andrew Holme]

I'm trying to apply a tally light system: a Panasonic video switcher
that sends a signal, and I want a couple of LEDs to turn on 150ft.
away whenever that signal is on. That's it.

Whether I'm building it myself or not, I need to understand what the
switcher does and doesn't handle, so I don't overload any of the
Panasonic's components - it's a $11,000 device. Here's the information
I have about its (D-sub15) control output:
http://www.drewlahat.com/misc/AV-HS400N_tally.GIF

Is it designed to drive LEDs directly, or would you recommend a relay?

That diagram shows it driving an LED (with a series current-setting
resistor) directly.

You could use a relay or an opto-isolator. I would go for the latter.
You'll need a local DC power source either way.

What should also be in there to protect the unit (diodes)?

A diode could protect against reverse polarity; you could also include
transorbs (transient absorbers) and use a screened cable with the screen
connected to chassis-earth at both ends.

The signal has to go through 150 ft. of 26 AWG (7x34) Stranded TC
wire, rated at 38.5 ohm/Mft.

I might be able to use an off-the-shelf tally system - Datavideo TB5
(http://www.datavideo.us/products/TB_5_main_page.htm). Since it's
designed to connect to their own video switcher, there isn't much info
available. All I have is the Datavideo switcher diagram, which the TB5
is designed for:
http://www.drewlahat.com/misc/Datavideo_switcher_Tally_pinout.GIF

Given the right cable, should I be able to connect the TB5 to the
Panasonic directly and suppose everything will work fine, or not
necessarily?

Looks like it.

They call it an RS232 cable; but it's not RS232. They might as well call it
VGA judging by the D-connectors.