MIller Solar Engine 1381 replacement?

[kaczchris]

I know BEAM robotics have fallen out of style a bit, but I hope someone is still mucking about with them because they are super cool. And if you don’t know what I am talking about check it out!

Right now I am working on a Miller Solar Engine and trying to find a replacement for the 1381-J voltage trigger. I tried out the DS1817. It was recommended to me by one of the technicians at Digi-Key as a replacement for the MN1381-J and on paper it looks like a good swap, but in the circuit it is just not resetting once the voltage drops. I have it breadboarded and I can stick the 1381 in it and it works perfectly. When swapped with the DS1817 it triggers once the top voltage is reached, but then never resets (it just drains forever.) I double-checked the component type to make sure it was just not a miss shipment of the wrong item, but it checks out. And I tried swapping the DS1817 component out thinking that I just had a dud (or 5) but it does not seem to help.

Any thoughts?

Here are the data sheets on the 2 items.
http://datasheets.maximintegrated.com/en/ds/DS1817.pdf
http://www.semicon.panasonic.co.jp/ds4/SAG00003CEM_discon.pdf

one bit of weirdness I already figured out is that the 1381 looks like it has a different 1-2-3 pin out sequence at the top of the PDF but it turns out it does not at the bottom. (just flipping the new component does not fix it)

Here is a link to a miller engine schematic:
http://www.beam-wiki.org/wiki/Miller_Solar_Engine

Thanks for your help!

 

[CDRIVE]

Quite frankly it blows my mind that a circuit that basic, that's based on an off the shelf chip, was named after the guy! By the way, there's a discrete version of it. In both cases they amount to a relaxation oscillator.

Chris

 

[kaczchris]

A discrete version of it?
forgive me as I do not know exactly what you mean by that.
Are you referring to the part swap or the whole circuit?
Thanks.

 

[davenn]

A discrete version of it?
forgive me as I do not know exactly what you mean by that.
Are you referring to the part swap or the whole circuit?
Thanks.

discrete = individual transistors etc .... no IC's


Dave

 

[CDRIVE]

Yes, as Dave explained. The path to the topic is on the schematic.

Chris

 

[(*steve*)]

There are many "voltage detector" devices out there which could be used.

You need one with some hysteresis or where this can be somehow finessed into the circuit.

It looks like most of the web pages are down :-( Many were last updated over 10 years ago...

Have you looked for the sites in the internet archive?

This site used to have lots of schematics, but now all I get are blank pages.

Even the internet archive doesn't help...

 

[CDRIVE]

After looking at the link in my schematic I realized that it's not a link to that thread. Here it is.
https://www.electronicspoint.com/easter-engine-problem-t251737p2.html#post1489892

I would advise reading the entire thread starting from page 1.

Chris

 

[kaczchris]

Thanks all for the good comments, I had actually searched and found the thread linked but did not find it fit what I am trying to do. The BEAM circuit is more than just a functional thing, it is also about the simplicity, elegance and efficiency of the design. The Miller engine is distinctive because of its small number of components and its efficiency (in fact with the setup i am using i do not even need the resistor so there is no energy loss to resistance at all.) Playing with such small bursts of electricity makes efficiency really important.

I think that the crux of the problem has been defined, I am looking for a voltage detector that will replace the discontinued 1381 with sufficient hysteresis to use in the relaxation oscillator called the Miller engine. I had thought I had found it with the DS1817, but for some reason that is beyond me it is not working. Any idea on why that component is not working (or of a more suitable replacement for the 1381?)

 

[kaczchris]

And yes, many of the BEAM pages are unfortunately fallow.

there was a lot of interest years ago, but i think the limits were quickly reached by many.
That being said there is still a lot of awesomeness that can be done with the circuit. the challenge becomes an engineering one where you have to translate this little tiny burst of energy into something interesting.

For reference here is a link to one of my projects using the Miller engine:

 

[CDRIVE]

For reference here is a link to one of my projects using the Miller engine:

That will revolutionize the world as we know it. Please make mine sunny side up and easy. Does it come with bacon and grits?

Chris

 

[(*steve*)]

(in fact with the setup i am using i do not even need the resistor so there is no energy loss to resistance at all.)

There's a false statement

Just because you don't have a resistor doesn't mean there's no resistance.

 

[kaczchris]

There's a false statement

Just because you don't have a resistor doesn't mean there's no resistance.

true. sorry if you thought i was saying there was no resistance in the circuit.
just not using a resistor which just "wastes" energy for heat in the grand scheme of things.

 

[kaczchris]

That will revolutionize the world as we know it. Please make mine sunny side up and easy. Does it come with bacon and grits?

Chris

no bacon and grits yet.
but pancakes yes!

 

[(*steve*)]

true. sorry if you thought i was saying there was no resistance in the circuit.
just not using a resistor which just "wastes" energy for heat in the grand scheme of things.

However a base resistor can save energy by limiting base current to the required value.

Excessive base current is at a minimum a waste, and at worst will damage the transistor.

It's not as simple as you might think...

 

[kaczchris]

It's not as simple as you might think...

it never is.


thus my problem with figuring out the "why does it not work" with the DS1817...

 

[kaczchris]

for a better look/explanation of the Miller engine i should have linked this page first:

http://www.solarbotics.net/library/circuits/se_t1_mse.html

 

[CDRIVE]

it never is.


thus my problem with figuring out the "why does it not work" with the DS1817...

Have you compared the data sheets between the two?

Chris

 

[kaczchris]

Have you compared the data sheets between the two?

Chris

to my limited ability I have compared them. (first thing I did)
I got the suggestion for the swap from a digi-key technician who I hope knows more than my limited electronics knowledge.

A friend of mine has mentioned that the 1381 is CMOS and the DS1817 is TTL, do you think that might be causing different behavior?

 

[CDRIVE]

The 138(n) series come with 1 of 3 output variations. CMOS(Push-Pull), NCHAN(Open Drain) and Inverted CMOS(Push-Pull).

The DS1817 is provided with CMOS Push-Pull output only. Typical output current appears to be about 350uA.

Is your circuit like this with the PNP eliminated?

http://www.solarbotics.net/library/circuits/se_t1_mse.html

Chris

 

[CDRIVE]

After comparing the data sheet waveforms between the 1381 and the DS1817 I now see what your problem is. As is (no additional circuitry) the DS1817 will not replace the 1381. There is nothing in your circuit to turn it off after it's triggered.

Chris