Building and testing my design for a handhold current indicating form of HRC Zapper that has dual duty cycle option

This is one of my best HRC-based zapper designs and made easy and cheap to build, starting with a "LED Flasher kit" from All Electronics 

(http://www.allelectronics.com/)  (cost about $3 for the kit although mostly just using the kit's printed circuit board and a few of its electronic parts.) I used a small plastic food storage container as its chassis.  Oddly, most of my records have vanished re this instrument's development done 2 years ago, so here is what is easily available right now for this page, and ought to be enough for someone with some familiarity with building electronic gizmos to reproduce it. At this point one would need to create their own parts list from the schematic and layout shown below, to build this gizmo.

It features a handhold current indicating LED, a buffered output for solid waveform, low battery usage CMOS IC circuit, and a dual duty cycle mode to select the usual 35% duty cycle and also its complementary waveform, 65% duty cycle. Frequency is set for the usual 30 KHz range pulse repetition rate, 9 Volt peak output.

Here is the layout and schematic.




Here it is upside down, but powered up and output also loaded by handholds, the green LED showing handhold current, its green light intensity is a function of the actual handhold current, providing feedback to the experimenter as to continuity of output circuit and load.


Inside of chassis showing battery compartment and handhold output connector, which is the handset connector used on older telephones; one might choose another kind of connector for the wires to the copper tubing handholds.


Sitting on the assembly diagram and schematic.


Oscilloscope showing the standard zapper 35% duty cycle output waveform. The 65% duty cycle waveform option is the inverse of this one; that is, the part that is low voltage here is the part that is the high voltage part of the waveform..


As examined a couple years later, here is the top of the zapper, showing label, and sitting on the descriptive printed assembly and schematic document which is kept inside the unit, folded up, to help with any troubleshooting needed in future years. This one uses the telephone handset connector for the standard output wire connection, so as to use the standard output wire harness and its snap connectors for connection to handholds or stick-on electrodes of various types in the experiments.


A front view of the zapper.


And a bottom view, with the bottom cover off, showing the fairly primitive construction yet does the job. This design was intended for possible use in emergency times, reproducable by others wishing to experiment with it, building their own.

Copyright © 2008 James E. D. Cline. Permission granted to reproduce providing inclusion of a link back to this site and acknowledgment of the author and concept designer James E. D. Cline.