TI 2230NZT 321581chip from Unisys RS488_422 security system box. What is it? - Page 1
Forum section: electronics / beginners

author: dentaku
author_rank: Frequent Contributor
timestamp: February 24, 2016, 11:43:26 pm
content: I found some old bits of a security system that got scrapped. One part is a board labeled Unisys/Convergent TC HUB from 1991 and it's covered in 74LS chips.Everything is duplicated 12 times with 13 LEDs and a big centronics connector along the edge.Next to eachDS3695N - Multipoint RS485_RS422 Transceiver-Repeaterthere's an 8 pin TI chip labeled2230NZT 321581that I'm curious about.I don't need this board for anything but I'm just curious what these ICs are because I can't find any info on them.I can't find any kind of input going into it but pin 1 is connected to pin 1 (1A) of a 74LS423N monostable multivibrator.Here's a rough sketch of what I can find that's connected to it.Does this look familiar to any of you?

author: HAL-42b
author_rank: Frequent Contributor
timestamp: February 25, 2016, 12:09:41 am
content: The three inductors look somewhat like a LVDT (differential transformer). As long as the signal on two of the coils is the same no voltage is induced on the third coil. As soon as the signals start to differ the difference is induced on the third coil.So the 2230 could be a plain op-amp, a bridge amplifier, a Schmidt trigger or anything really.

author: xygor
author_rank: Regular Contributor
timestamp: February 25, 2016, 02:48:32 am
content: Quote from: HAL-42b on February 25, 2016, 12:09:41 amNot an LVDT. LVDT measures physical displacement. That's just a 3 winding transformer that may be wired in a differential way.Never mind that, what are those funky looking torroids!? (looks like maybe TDK is mfr.)

author: dentaku
author_rank: Frequent Contributor
timestamp: February 25, 2016, 02:54:34 pm
content: Quote from: xygor on February 25, 2016, 02:48:32 amI think they say TOKIN. I've seen little toroids like that in other products in the past.As for the PCA EPA267B, it's just three windings, not connected together in any way, in a potted box with 6 pins.Pins 5 and 6 are connected to the 2230NZT pins 6 and 7 through 200ohm resistors.I think I'll trace out where the other two windings are going.

author: xygor
author_rank: Regular Contributor
timestamp: February 25, 2016, 11:25:53 pm
content: Quote from: dentaku on February 25, 2016, 02:54:34 pmThanks.But what are the blocks on either side of the toroid? Is that just part of the case?

author: dentaku
author_rank: Frequent Contributor
timestamp: February 25, 2016, 11:34:10 pm
content: Quote from: xygor on February 25, 2016, 11:25:53 pmYup, it's just plastic that holds it all in place and also the 4 pins are attached to it.

author: dentaku
author_rank: Frequent Contributor
timestamp: February 26, 2016, 01:48:39 am
content: Well, there's too many inductors and such with most traces on the top of the PCB hidden under components to bother tracing out the rest of the circuit but I DID put a 2230NZT and one of the little 6 pin transformers in a breadboard following the circuit diagram I posted in my first message and found that any quickly rising or falling signal going into either of the two other windings of the PCA EPA267B creates sharp spikes on the winding connected to pins 6 and 7 of the 2230NZT and causes what I'm assuming is the output (pin 1) to flip from high to low which makes sense because it the goes to an input of an74LS423 monostable.SO...Running at 5V, the output of pin 1flips from 0V to roughly 4.2V. If I remove the transformer from the circuit and directly connect a 2.4V or higher square wave into pin 6 (leaving 7 floating) the output is NOT inverted and the same signal into pin 7 creates an inverted output on pin 1. It's like a comparator that's set to flip at 2.4V (maybe it's set for half VCC?) on fast rising edges.This only works with square waves, triangle or sine do nothing and switching from ramp to saw makes it either latch to high or lowI'm assuming because saws and ramps only have one quickly rising or falling edge.Some kinda comparator? I don't know enough about this kind of stuff.