Boolean Logic Probe/Scope Trigger

Boolean Logic Probe/Scope Trigger FLASH: Imitation is the best flattery. The Combinatorial Logic Probe, first announced in the November 1993 edition of Nuts & Volts Magazine, now has at least one copy. JDR Microdevices is now selling the SuperProbe Basic-8 logic trigger for $79.95. There are differences, of course. The SuperProbe has grabbers instead of dip-clip push-ons, and switches for the logic levels. As such, it takes up a bit more space in your toolbox. (And of course it costs over twice as much!)

Alex Funk DESIGN

BACK TO INDEX

Alex Funk DESIGN
WebPages are all

MODEM FRIENDLY

and most of the grafix herein are original.

The Combinatorial Logic Probe / Scope Trigger Pod

(For Five volt logic)
The Combinatorial Logic Probe / Scope Trigger Pod can be thought of as a poor person's logic analyzer in that it gathers the handful of qualifiers like register address, bank enable, chip select, IO / memory, or read/write you usually need to trigger on digital logic, without having to carry a logic analyzer. A combinatorial logic probe capable of monitoring logic lines on nine protected inputs for a coincidence of up to four highs and five lows, it provides visual indication of states as short as 20ns, for use without a scope, via a superbrite LED. While the trigger output is unconditionally true, the LED extinguishes at duty rates higher than 100 flashes per second to prevent overloading it.

The unit has no switches: in order to detect a low, for example, the user attaches one of the low inputs to a DIP clip line that will go low during the logic state of interest. Don't care inputs are simply left unconnected. An on-board current-limited triangle wave generator (Ramp Out) back-drives monitored logic under test to distinguish when a bus line is tristated and floating high / low rather than driven high / low. During tristated (high Z) periods on the line, the superimposed triangle wave shows on the user's scope. The 2 x 1.2 inch circuit board takes little tool kit space.

The Input Cable

Both kit and assembled unit include parts for a 18" removable mass-terminated ribbon cable with 13 0.025 inch insulated color-coded sockets which is user-assembled.

Trigger out is available on a 6-pin dual in-line male header connector (3x2 0.025" square posts on 0.1" centers)

Wire No.	Sleeve Color	Description
1	Brown	Signal generator ramp out
2	Black	Mandatory PWR GROUND connection
3	Gray	Low input
4	White	High input
5	Gray	Low input
6	White	High input
7	Red	V+ mandatory power input
8	--	no connection
9	Gray	Low input
10	White	High input
11	Black	Mandatory Low input
12	White	High input
13	Gray	Low input
14	Brown	Trigger signal out

The pod is powered by device under test. The kit has 21 pre-installed surface mounted components. $22 (Kit #9307) or $35 for kit with circuit board assembled and tested (Kit #9307AT) postpaid. Unit is shipped upon receipt of your check.