300v Peak to Peak Signal Generator  -  This circuit converts a square wave signal to a +-150 volt output signal with fast 100nS rise and fall times . . . [Circuit by David Johnson P.E.,  06/03/00]

AC Current Indicator Light  -  This circuit could be wired into a 120vac power line, which feeds power to any load, ranging from 40 watts to 250 watts.  It will turn on a LED light whenever current is being drawn by a load.  It is especially useful for remote lights, where you may not . . . [Hobby Circuit designed by Dave Johnson P.E.,  10/16/05]

Advertising Badge with Flashing LED #1  -  I have seen numerous flashing light badges at trade shows and conventions. They are often handed out as gifts to promote some business. The devices often use inefficient circuits, which cause the battery power source to be quickly depleted . . . [Circuit by David Johnson P.E.,  03/26/02]

Advertising Badge with Flashing LED #2  -  This circuit uses a CD4013 dual D Flip/Flop IC.  A single lithium battery will provide months of continuous LED flashing.  It also has a tiny push-button switch to turn on and off the light flashing . . . [Circuit by David A. Johnson P.E.,  03/26/02]

Battery-Powered LED Flashing Advertising #2  -  This circuit is similar to flashing LED advertising badge #1.  It uses a CD4013 dual D Flip/Flop IC.  The 74HCT74 IC in #81 does not always work.  As in #81, a single lithium battery will provide months of continuous LED flashing. . . . [Hobby Circuit designed by David A. Johnson P.E.,  03/26/02]

Characteristics of CMOS Logic Inverter Amplifiers  -  This chart shows some of the measured characteristics of three different unbuffered CMOS logic gates, used as voltage amplifiers . . . [Hobby Circuit designed by David Johnson P.E.,  02/11/02]

CMOS Logic Inverter Amplifier Characteristics  -  This chart shows some of the measured characteristics of three different unbuffered CMOS logic gates, used as voltage amplifiers . . . [Circuit by Dave Johnson P.E.,  02/11/02]

Flashing LED Advertising Badge #1  -  I have seen numerous flashing light badges at trade shows and conventions. They are often handed out as gifts to promote some business. The devices often use inefficient circuits, which cause the battery power source to be quickly depleted . . . [Hobby Circuit designed by David Johnson P.E.,  03/26/02]

Form Push-Pull Driver using N-Ch And P-Ch Transistors   -  This circuit can produce high speed output signals with fast rise and full times. The unique change pump action allows the voltage of the upper P-ch device to range from millivolts to hundreds of volts. The output current is only limited by the rating of . . . [Hobby Circuit designed by David A. Johnson P.E.,  06/27/00]