Let's Make Robots!

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nintwala's picture

do you know of a 74HC240N solar engine that does not use a 1381 voltage trigger? I was reading this page http://www.beam-wiki.org/wiki/Power_Smart_Heads and according to it, there is suppose to be a solar engine that doesn't require 1381s... "A SPSH4 design is next that replaces the 1381 with two transistors and provides dual motor drivers." I cant seem to find that circuit. Can anyone help?

Sorry if this is not appropriate to ask here.

Yahmez's picture

The original Solar Power Smart Head circuit uses a transistor/240 based SE. You might try that one out. The circuit does essentially the same thing one as the one I used for this guy.

As far as I know, there was never a completed SPSH v4.


koo1man435's picture

I may not be the best person to answer, but I made a robot using a similar circuit to this one.  Instead of a 74HC240, I used a 74AC240, and I didn't need any motor drivers to run the motor.  There also is a solar engine called the FRED solar engine.  I have been impressed with its efficiency, and all of the parts are available at radioshack.  However, don't get it mixed up with the FLED solar engine, which is rediculously inefficient.

nintwala's picture

Is this the FRED you are talking about? http://raysbeambots.solarbotics.net/FLEDtutorial.htm

I have worked with FLED engine before, but wasnt very happy with it. I am assuming they both use flashing LED in the circuit, correct?


koo1man435's picture

yes they both use a flashing LED.  I found that red works a little better than green.

koo1man435's picture

yes it is.  You only need to build one of the solar engines, not both though.



ignoblegnome's picture

Lots of useful BEAM stuff at this wiki site.

nintwala's picture

thanks, there is sooo much stuff around! trying get wrap my mind around it.

nintwala's picture

this is awesome! Is there anyway you can make a parts list of what you used? I see you used a 74HC... chip. Is there anyway you can make something similar without that chip? 

koo1man435's picture

it uses a 74XX240, which is 6 inverter gates in one 20 pin chip.  You could wire a NAND gate into an inverter by connecting both inputs together with a wire.  Or, if you really want to get DIY, you could make 6 NAND gates out of transistors and wire both inputs together.  I built this circuit, and it works pretty well with about 5 volts.  Link to schematic for the gates can be found here.