Circuit: Shok

Dave Hrynkiw
July 12, 2007

ShokPopper & ShokPhoto-head

You want a simple Photovore? This very tidy design by Solarbotics' own Grant McKee is based on a technique developed by Mark Tilden - Shok architecture:

Here's video of the test robots being tuned as a 177kB Windows Media Format (WMV) file or as a 168kB RealMedia (RM) file.

ShokPopper V1.0 (click for circuit diagram) - GrantM Aug 2001

Theory of operation:
"Shok" architecture is a technique pioneered by Mark Tilden describing controlled state changes of Bicore style circuits via chip power or enable toggling. When a Bicore circuit is powered on, it will resume a state opposite to what it was when it was powered off, this effect can either be duplicated by pulsing the enable line or by pulsing power to the chip itself. This is called "shoking" the Bicore. The power-on state can also be pre-determined by biasing the voltage across the Bicore capacitors. A photodiode attached directly across the Bicore charge capacitor will pre-bias the shoked output. The addition of tactile sensors is easily implemented by attaching a switch from the input of the Bicore to +Vdd. When the switch is closed, it forces that side high, presetting the state of the Bicore on the next pulse cycle.

Probably one of the simplest photovore circuits to date, the core circuit consists of a 6 part count and a solar-engine. Either 74AC240 or 74HCT240 will work but we recommend using the AC series for better output drive current. The ShokPopper will not work under battery power unless the enable line is pulsed.

Solar Engine to use with Shok:
The best solar-engine to use is the Miller engine. For the ShokPopper Photovore we used a Miller engine consisting of:

  • CP3300uf cap
  • 1381Q
  • CP1µf timer cap (0.47µf will work fine as well)
  • 2N2222 Transistor
  • SC3733 Solarcell
  • D1 1N914 Diode

The Bicore Circuit Consists of:

  • 74AC240 Octal Buffer Chip
  • TR100k Trimpot
  • 2 x 0.22µF Capacitors
  • 2 x IR1 Infrared Sensors
  • 2 x RM1 Motors
  • TACT2 Spring Sensor Kit (Optional)

The Miller engine switches the ground line of the circuit.

The theory of operating is very similar to that of the shok popper except that the head now only uses one motor, the photo head does not "lock" on but will continually seek for the brightest source of light. Nice effect if you want a continually seeking, dynamic device on a stationary base.

  • 74AC240 Octal buffer chip
  • 4 x CP0.1µF capacitors
  • 100k resistor
  • 2 x 47k resistors

MORE POSTS

September 13, 2005
Pendulum project

It's really nice to receive pics of projects people have built out of our book "Junkbots". Here's one of the latest: the Pendulum by Christopher Pepe. Nice magnetic suspension mechanism! Read More...

January 22, 2014
Wednesday Links: Marble Track Table, Fil...

Technology empowering cats! Cats should have the right to tweet! Or at least have a live video stream dedicated to their cat-like doings and goings. All with the help of Arduino Yun.This is just one of the many things (five is considered many, right?) that we have for you today: Wooden Table Carved with Marble […]

October 4, 2001
Push Pogo Pins Update

We've received word that we will be receiving new stock on all our push pogo pins, but they will not be available for order until October 8 or 9th. The order link will be restored when the inventory arrives.

September 23, 2003
Solarbotics goes to San Francisco!

Solarbotics recently sent a representative to the Robot Society of America's Robot Expo in San Francisco. Wanna see some pics? Check them out here at http://www.solarbotics.net/gallery/SanFranciscoRSA.

1 6 7 8 9 10 253
Solarbotics Ltd Logo
Solarbotics has been operating for more than 25 years, bringing electronics know-how and supplies to both the electronics professional and hobbyist. We'll be happy to help you too!

Solarbotics, Ltd. is not responsible for misprints or errors on product prices or information. For more information, please see our Terms and Conditions.

Warning: This product contains chemicals known to the State of California to cause cancer and birth defects or other reproductive harm.
Please visit www.P65Warnings.ca.gov for more information. This item was manufactured prior to August 31, 2018.