How do Mod Tap UTP Testers work?

[cpvh]

For the uninitiated, I am referring to UTP cable testers which have a Master unit with a red LED and a red LED for each UTP pair, and a remote unit with a green LED for each pair.

For each pair that is present and correct polarity, a green light on the Master unit will light, if the polarity is reversed, then the red LED lights instead.

Does anyone know (simple explanation please, my electronics knowledge is basic) how this is acheived?

TIA

[The Natural Philosopher]

Are you serious?

[Dave Liquorice]

knowledge

Basic electronic knowledge hasn't LED him to discovery LEDs that light green in one direction red in the other? Or if discreet LEDS, diodes in series.

[cpvh]

each pair that is present and correct polarity, a green light on >> the Ma ster unit will light, if the polarity is reversed, then the red >> LED ligh ts instead. >> >> Does anyone know (simple explanation please, my electroni cs knowledge >> is basic) how this is acheived? > > Are you serious? Basic electronic knowledge hasn't LED him to discovery LEDs that light green in o ne direction red in the other? Or if discreet LEDS, diodes in series. -- Ch eers Dave.

Hmmm....

The Master has a battery, the remote has none.

I can see that just having a loop on each of the 4 sets of pairs of contact s in the Remote would allow a LED to denote continuity, but how (without a microprocessor and power at the far end) do you determine polarity?

[Harry Bloomfield]

I've got one, but its been a while since I needed to use it...

They use a cmos logic IC who's output pins cycle through one core at a time, making them a logic one. At the far end, that unit links that logic 1 back via the second wire of the pair back to the main unit. The main unit then monitors what comes back and ensures the 1 comes back on the correct core - flagging a fault if not, or if a logic one appears on more than one core ( short between cores).

Hope that makes some sense?

No need for a microprocessor, just simple logic gates and an oscillator. I built something similar in the 1960's using nothing more than wafer switches and low voltage lamps.

[cpvh]

On Friday, February 7, 2014 10:52:02 AM UTC, Harry Bloomfield wrote:

uary 2014 15:37:05 UTC, Dave Liquorice wrote: >> On Thu, 06 Feb 2014 14:51:

43 +0000, The Natural Philosopher wrote: >> For >> each pair that is presen t and correct polarity, a green light on >> the >> Master unit will light, if the polarity is reversed, then the red >> LED >> lights instead. >> >> D oes anyone know (simple explanation please, my >> electronics knowledge >> is basic) how this is acheived? > > Are you >> serious? Basic electronic kn owledge hasn't LED him to discovery LEDs that >> light green in one directi on red in the other? Or if discreet LEDS, diodes >> in series. -- Cheers Da ve. > > Hmmm.... > > The Master has a battery, the remote has none. > > I c an see that just having a loop on each of the 4 sets of pairs of contacts > in the Remote would allow a LED to denote continuity, but how (without a > microprocessor and power at the far end) do you determine polarity? I've g ot one, but its been a while since I needed to use it... They use a cmos lo gic IC who's output pins cycle through one core at a time, making them a lo gic one. At the far end, that unit links that logic 1 back via the second w ire of the pair back to the main unit. The main unit then monitors what com es back and ensures the 1 comes back on the correct core - flagging a fault if not, or if a logic one appears on more than one core ( short between co res). Hope that makes some sense? No need for a microprocessor, just simple logic gates and an oscillator. I built something similar in the 1960's usi ng nothing more than wafer switches and low voltage lamps. -- Regards, Harr y (M1BYT) (L)

Thanks for the reply Harry,

What this device appears to have is some active electronics at the master e nd, which I can see might send a logic 1 up say the left leg of a pair. at the remote end, it has a passive device, 4 red LEDs, 4 green LEDs and 4 re sistors. I assume the LEDS are in Parallel across the inputs with a red in one direction and a green in the other. I can see how if 1 appears at the l eft leg at the remote end, then the green will light, but if it's reversed then the red will light.

But how does the master end manage to give the same display simultaneously? As far as I can see all it would "see" would be continuity in either case .

Then again, perhaps I don't understand your initial explantion suficiently (I have a very very vague understanding of logic 1 and 0 and gates).

Chris

[cpvh]

[e-mail] presented the following explanation : > On Thursday, 6 February 2014 15:37:05 UTC, Dave Liquorice wrote: >> On Thu, 06 Feb 2014 14:51:43 +

0000, The Natural Philosopher wrote: >> For >> each pair that is present an d correct polarity, a green light on >> the >> Master unit will light, if t he polarity is reversed, then the red >> LED >> lights instead. >> >> Does anyone know (simple explanation please, my >> electronics knowledge >> is b asic) how this is acheived? > > Are you >> serious? Basic electronic knowle dge hasn't LED him to discovery LEDs that >> light green in one direction r ed in the other? Or if discreet LEDS, diodes >> in series. -- Cheers Dave.

ee that just having a loop on each of the 4 sets of pairs of contacts > in the Remote would allow a LED to denote continuity, but how (without a > mic roprocessor and power at the far end) do you determine polarity? I've got o ne, but its been a while since I needed to use it... They use a cmos logic IC who's output pins cycle through one core at a time, making them a logic one. At the far end, that unit links that logic 1 back via the second wire of the pair back to the main unit. The main unit then monitors what comes b ack and ensures the 1 comes back on the correct core - flagging a fault if not, or if a logic one appears on more than one core ( short between cores) . Hope that makes some sense? No need for a microprocessor, just simple log ic gates and an oscillator. I built something similar in the 1960's using n othing more than wafer switches and low voltage lamps. -- Regards, Harry (M

1BYT) (L) Thanks for the reply Harry, What this device appears to have is some active electronics at the master end, w hich I can see might send a logic 1 up say the left leg of a pair. at the r emote end, it has a passive device, 4 red LEDs, 4 green LEDs and 4 resistor s. I assume the LEDS are in Parallel across the inputs with a red in one di rection and a green in the other. I can see how if 1 appears at the left le g at the remote end, then the green will light, but if it's reversed then t he red will light. But how does the master end manage to give the same disp lay simultaneously? As far as I can see all it would "see" would be continu ity in either case. Then again, perhaps I don't understand your initial exp lantion suficiently (I have a very very vague understanding of logic 1 and 0 and gates). Chris

Oops!

Having just checked the units, it's only the remote that has the red LEDs, Master just has green. Obviously they couldn't figure out a way to show re versed at both ends either !:^*>))

[Capitol]

[e-mail] wrote:

sor and power at the far end) do you determine polarity? I've got one, but its been a while since I needed to use it... They use a cmos logic IC who's output pins cycle through one core at a time, making them a logic one. At the far end, that unit links that logic 1 back via the second wire of the pair back to the main unit. The main unit then monitors what comes back and ensures the 1 comes back on the correct core - flagging a fault if not, or if a logic one appears on more than one core ( short between cores). Hope that makes some sense? No need for a microprocessor, just simple logic gates and an oscillator. I built something similar in the 1960's using nothing more than wafer switches and low voltage lamps. -- Regards, Harry (M1BYT) (L)

Thanks for the reply Harry, What this device appears to have is some active electronics at the master end, which I can see might send a logic 1 up say the left leg of a pair. at the remote end, it has a pas sive device, 4 red LEDs, 4 green LEDs and 4 resistors. I assume the LEDS are in Parallel across the inputs with a red in one direction and a green in the other. I can see how if 1 appears at the left leg at the remote end, then the green will light, but if it's reversed then the red will light. But how does the master end manage to give the same display simultaneously? As far as I can see all it would "see" would be continuity in either case. Then again, perhaps I don't understand your initial explantion suficiently (I have a very very vague understanding of logic 1 and 0 and gates). Chris

I always use one of these.

Works in a similar manner by passing a test pulse from one pin on the connector to the same pin at the other end. When correct, each led will light up in sequence. Operates at two frequencies, to check cable losses I guess. If you've got it wrong, you always have to chop the connector off and reterminate, if recrimping the connector doesn't give you a pass.

[Dave Plowman (News)]

I have a Maplin cable tester which 'clocks' through each conductor in turn

- dating from before CAT6 cabling. I expect much of the principle is the same. Could send you a scan of the circuit if you want.

[Dave Plowman (News)]

I have one which looks the same - bought when I cabled the house for broadband some years ago. Cost a lot more than that, though. ;-)

[Capitol]

Yes, so did mine. The price has really come down.

[Bob Eager]

I made a couple of boxes, one with four toggle switches and a battery, the other with four pairs of red and green LEDs. SWMBO on switches, sequanece and combination, me on the lights.