# Glimmies, As Logic

[Jacob Christ] writes in with a hack that’s going to be this summer’s fidget spinner. Why? The favourite toy of his youngster’s generation is a Glimmie. And while fidget spinners were useful for, well, spinning, the small animal-like Glimmie seems to have an unexpected property, they can function as logic gates.

They form an optical inverter, in their head is a phototransistor and in their belly an LED which goes on when the head is in the dark. He’s found through experimentation that they can be combined to form an AND gate, and thus a NAND gate with the addition of a further inverter.  Since all logic functions can be made from NAND gates, it should therefore be possible to go as far as to make any device based upon logic, even up to a fully functional computer. He estimates the cost of a single gate at \$16.30. A computer would require in the region of 80,000 Glimmies to work, but maybe someone with deep enough pockets will be foolhardy enough to give it a try.

You can see the AND gate in action below complete with camera work from a youngster, and if unexpected logic gates are something that’s caught your attention you can take a look at the battery booster pack logic we brought you a while back.

## 10 thoughts on “Glimmies, As Logic”

1. McErer says:

And now build an oscillator!

1. jacobchrist says:

Actually the first thing I built. Took 5 Glimmies couldn’t quite pull it off with three. Not sure if it actually isolated or just became steady state since I do not have a scope handy.

2. jacobchrist says:

Actually the first thing I built. Took 5 Glimmies couldn’t quite pull it off with three. Not sure if it actually oscillated or just became steady state since I do not have a scope handy.

2. Jeffo says:

Maybe Glimmies will reset Moore’s law

3. To a degree, this toy functions as a nor gate, since it can take more then one input.
And nor gates can be used to build any other gate. So no need to take the extra mile with building nand gates first.

(A nand gate can be build with inverters on all inputs and outputs of our nor gate. So it would need 4 nor gates. An and gate needs only 3 nor gates, and an inverter needs only 1. (An xnor on the other hand is though more complicated…))

4. Pat says:

” it should therefore be possible to go as far as to make any device based upon logic, even up to a fully functional computer.”

Pretty sure there are actually two requirements gates to be able to build anything: first, you need to be able to build a NAND or NOR gate, and second, that gate needs to have a drive capability of at least 2. If you can only drive one load, you’re screwed. In this example, for instance, the ‘output’ Glimmie would need to be able to feed two separate Glimmie gates in order for it to work.

If the light level needed to trigger the next Glimmie is equal to a full Glimmie output (or anything more than half), for instance, it wouldn’t work. The NAND gate would still be buildable, but you couldn’t do anything with it. Imagine the NAND gate built with Glimmie A and B, feeding into Glimmie C, which feeds Glimmie D as an inverter. Either A or B can drive C (which drives D), but if you try to, say, build a latch, Glimmie D would have to feed both the *other* NAND in the latch *and* the output, and that wouldn’t work.

He’s demonstrated the one case (two bellies feeding one head), but not the other (one belly feeding two heads).

1. TacticalNinja says:

I never expected bellies and heads ever to be used to explain logic. Gave me a chuckle.

2. jacobchrist says:

Challenge accepted.

5. Hasn’t Julian Ilett demonstrated how to use Joule Thieves as logic gates?