raoul@eplunix.UUCP (Nico Garcia) (05/25/91)
There's a design for a multiple line use detector in a recent issue of Popular Electronics: page 21 of the July issue. Unfortunately, one of the chips mentioned is the SK2086. As near as I can tell from my latest ICMaster, it's a set of transistors. Unfortunately, the pinout is different for different manufacturers. The diagram is very unclear on the actual function of the chip. The article itself describes the chip as opto-isolators. Can anyone out there identify the manufacturer and actual function of the !@#$ thing? Others may have noticed that in-use indicators appear everywhere all the time. True: but ones that can be hooked in parallel with your phones, *and draw no DC current in the on-hook state* are rare. In series is easy, but that means tapping the phone line before it gets spread around your house. Voltage dividers are easy too, to get the signal down to something you can read easily: but that means connecting the thing to ground somewhere (not a great idea) and drawing current. Of course, the designer of this circuit could be using an office system, which doesn't care if you draw a little bit of DC: but then it's not very useful for hooking up to Bell systems, is it? -- Nico Garcia Designs by Geniuses for use by Idiots eplunix!cirl!raoul@eddie.mit.edu
mcovingt@athena.cs.uga.edu (Michael A. Covington) (05/25/91)
They almost certainly mean the SK2086 in RCA's popular "SK" series of replacement semiconductors. -- ------------------------------------------------------- Michael A. Covington | Artificial Intelligence Programs The University of Georgia | Athens, GA 30602 U.S.A. -------------------------------------------------------
caine@hplabs.hpl.hp.com (Nate Caine) (05/25/91)
SK2086 is an RCA replacement part number for a
Dual Photo-Darlington OptoIsolator.
_ _
anode1 1| U |8 emitter1
cathode1 2| |7 collector1
cathode2 3| |6 collector2
anode2 4|___|5 emitter2
The photo-darlingtons are NPN.
Limit Conditions
================
Pt 400mW Device Dissipation
Viso 7500V Peak Isolation Voltage
Input LED
=========
If 60mA Max DC Foward Current
Vr 3V Max Reverse Voltage
PhotoTransistor Characteristics
===============================
VCBO 30V Collector to Base Voltage
VCEO 30V Collector to Emitter Voltage
IC 30mA Continuous Collector Current
hFE 50 Typical DC Current Gain
BW 200KHz Typical Bandwidth
These optoisolators are intended for use in isolating audio and video
inputs from a VCR to a HOT chassis TV set.grayt@Software.Mitel.COM (Tom Gray) (05/28/91)
In article <1081@eplunix.UUCP> raoul@eplunix.UUCP (Nico Garcia) writes:
:There's a design for a multiple line use detector in a recent issue
:of Popular Electronics: page 21 of the July issue. Unfortunately,
:
:Of course, the designer of this circuit could be using an office
:system, which doesn't care if you draw a little bit of DC: but then
:it's not very useful for hooking up to Bell systems, is it?
Draw less than 4mA from the loop and you will not have any
problems.