253 replies to this topic

[Frozentech]

I am thinking of building a bp speed tester, instead of using a stopwatch and microswitches i will design a digital counter. I am hoping to start and stop the timer using photodiodes that detect either the orange light from burning bp or the IR given off. This will be very accurate and will last and last. Any thoughts? It could be used as 'the' tester when the BPS is up and running.

I think it's a great idea, and I would have gone with a 'from scratch' timer, except I got a stopwatch on eBay for cheap. One thought on the photodiode sensor is that you might have to make a shield with a narrow slit to prevent triggering when the flame front is at an arbitrary distance from the sensor. Or some way to collimate the light ? Something to keep it from triggering until the closest point of approach or perpendicular to the sensor is what I mean ( sorry I am not making it clear... rum & coke tonight Perhaps just something like a tubular hood / shade ?

Anyway, sounds like a good project.

[EnigmaticBiker]

I am thinking of building a bp speed tester, instead of using a stopwatch and microswitches i will design a digital counter. I am hoping to start and stop the timer using photodiodes that detect either the orange light from burning bp or the IR given off. This will be very accurate and will last and last. Any thoughts? It could be used as 'the' tester when the BPS is up and running.

I haven't done much with electronics but I can probably lay my hands on a glass (borosilicate most likely) covered photodiode used in oil heating systems for detecting the flame. If you're interested I can run a multimeter over it and give details.

I suppose the accuracy would be dependant on the speed of detection, good idea and potentially very consistent measurement.

A neighbour services heating systems so I might be able to get them free!

Simon

[sasman]

You dont need to go to all the hassle if you have a video camera..When i first started making BP i was going to make a test rig like that on dan williams but there is no need..

All you have to do is measure out a fixed amount of BP in to a trough,angle iron etc.. I used a small U shaped brass section from B&Q..The longer the piece the more accurate will be your timing .
Mine was about 3 foot long..I simply poured my BP into the U shaped section making it spread out nice and even..
I then just lit 1 end of the Bp and filmed it with a video camera.. easy...When i first run the test i compared my times to Dan williams results my BP was very slow.. ..

I was very worried I had made a nice Big Ball mill 30+ Lbs pounds of hand cast lead balls 9" Barrell Home made Willow charcoal.. and it was really slow..But luckily I had Taken a 4" Minster Mine (Cat 3 Consumer firework) To bits and Had well over an ounce of Lift powder from that firework..

I then did the same test with the Commercial BP which was about 20 to 30 mesh..Watching it burn there was not much difference between The Commercail stuff and My own.. on closer video frame by frame there was possibly half a frame in it?.. It depended when you started the timing But basically My BP was as Fast or faster than the Real stuff..

Yet if i had took any notice of Dans results i would have thought my BP was very poor..The speed of the Burn depends on many factors amount of powder width&depth of the channel etc.. Lots of variables.. So i think it is very hard to create a accurate standard test...

But the test i performed would be accurate enough for me to measure my powder..In Practice i found that my Batch to Batch constistancy was perfect.. i could not measure any difference between batches..It all comes down to constistancy...

This year i am not going to use any of my Homemade Charcoal i have obtained some Commercial Vine charcoal. I will run the same test as i did last year to see how it compares..But i think that if your BP works for what you are trying to do then it is good enough.. Constistancy is much more important..

[karlfoxman]

I haven't done much with electronics but I can probably lay my hands on a glass (borosilicate most likely) covered photodiode used in oil heating systems for detecting the flame. If you're interested I can run a multimeter over it and give details.

I suppose the accuracy would be dependant on the speed of detection, good idea and potentially very consistent measurement.

A neighbour services heating systems so I might be able to get them free!

Simon

Yeah Simon send post the details, will need to be heat proof. Be nice to have a good testing platform, it will be reliable and well made so you will not have to change parts for a long time. The electronics would be best running of a 12v supply and will require no more than 200ma i should think, i will get my father to design the circuit and we will draw some pcb and schematics up in CAD. It wont be for a while but as soon as the electronics are on computer i will post the design. What should the length of the L angle be?

Karl

[Frozentech]

Yeah Simon send post the details, will need to be heat proof. Be nice to have a good testing platform, it will be reliable and well made so you will not have to change parts for a long time. The electronics would be best running of a 12v supply and will require no more than 200ma i should think, i will get my father to design the circuit and we will draw some pcb and schematics up in CAD. It wont be for a while but as soon as the electronics are on computer i will post the design. What should the length of the L angle be?

Karl

I have never seen a fixed standard for a burn trough type tester, Lady Kate used 2.5 feet, others in the US used 1 yard, how about a 1 meter distance so we can easily convert to cm/sec burns ? Allow an extra 50 cm perhaps for the flame front to stabilize before the 'start' sensor. Will your circuit be sophisticated enough to output in distance/time like a regular chronograph ?

[karlfoxman]

I have never seen a fixed standard for a burn trough type tester, Lady Kate used 2.5 feet, others in the US used 1 yard, how about a 1 meter distance so we can easily convert to cm/sec burns ? Allow an extra 50 cm perhaps for the flame front to stabilize before the 'start' sensor. Will your circuit be sophisticated enough to output in distance/time like a regular chronograph ?

I can get it to output almost anything using IC's, it would not be hard to have a few different outputs. What would everyone want to see? If i have a list i can add them to the design. I think one meter is fine, and yes an extra few cm would be good, maybe not 500mm though

cm/sec
meter/sec
feet/sec

To list a few, anything else you want please suggest here.

Karl

[EnigmaticBiker]

Yeah Simon send post the details, will need to be heat proof. Be nice to have a good testing platform, it will be reliable and well made so you will not have to change parts for a long time. The electronics would be best running of a 12v supply and will require no more than 200ma i should think, i will get my father to design the circuit and we will draw some pcb and schematics up in CAD. It wont be for a while but as soon as the electronics are on computer i will post the design. What should the length of the L angle be?

Karl

Karl,

I found that heating flame detector and remembered it incorrectly.
It is a photoresistor, gives readings of between ~50 Ohm in very bright light and open circuit in darkness, the response seems exponential.

Although it works adequately with the test voltage from my meter I think it is a 240v item.
The width of the outer glass bulb is ~10mm and it is housed in a tough heat resistant housing.
It is a "Satronic 1" FZ7116 943.

I will send a picture if it's of any use.

Simon

[karlfoxman]

Karl,

I found that heating flame detector and remembered it incorrectly.
It is a photoresistor, gives readings of between ~50 Ohm in very bright light and open circuit in darkness, the response seems exponential.

Although it works adequately with the test voltage from my meter I think it is a 240v item.
The width of the outer glass bulb is ~10mm and it is housed in a tough heat resistant housing.
It is a "Satronic 1" FZ7116 943.

I will send a picture if it's of any use.

Simon

The housing could be useful to hold a photodiode, i am really looking for photodiode as these can switch very fast indeed. I am unsure if i sould have it detecting visible light or IR. Post a picture of the item you have, its worth a look.

[EnigmaticBiker]

The housing could be useful to hold a photodiode, i am really looking for photodiode as these can switch very fast indeed. I am unsure if i sould have it detecting visible light or IR. Post a picture of the item you have, its worth a look.

Can't post pics cause I haven't got them hosted, I can email them.

Not sure about which light frequency to detect, I imagine that it would depend on how sensitive the component is. If visible frequencies, light leakage to the detector could be a problem. If IR, repeated firings could heat up surroundings and cause spurious detection.


Simon

"one time in the desert we lost our corkscrew and had to live on food and water for weeks"
W C Fields

Edited by EnigmaticBiker, 01 January 2007 - 01:28 AM.

[Andrew]

There are some photodiodes that can switch in 5ns that cost about 75p each if you buy one. Almost all the IR ones you can get are not the type that will be affected by 100 degrees of radiant heat; they all work in the near IR field. The radiation temperature to make them switch is in the order of a couple thousand degrees. Surrounding heat and daylight will not trigger them. The SFH203 is very good; I have used these on many occasions, it also has an ND filter to help cut any excessive optical radiation causing it to switch. The SFH485-2 is a good emitting diode to use with this photodiode. The pair operates at about 880/850nm, which is the sort of wavelength that even the best IR night vision cameras cannot see; so daylight is not really a problem.

If you?re worried about repeat firings accumulating heat and causing false readings, you?re worrying about the wrong thing!!!! Laying a new line of BP on a hot guide is potentially suicide, if not, definitely a loose all your hair idea, and probably skin!!! You should always let the guide cool, or use a new one; to avoid accidents/injuries. By being sensible, there wouldn?t be any heat building up anyway.

[EnigmaticBiker]

There are some photodiodes that can switch in 5ns that cost about 75p each if you buy one. Almost all the IR ones you can get are not the type that will be affected by 100 degrees of radiant heat; they all work in the near IR field. The radiation temperature to make them switch is in the order of a couple thousand degrees. Surrounding heat and daylight will not trigger them. The SFH203 is very good; I have used these on many occasions, it also has an ND filter to help cut any excessive optical radiation causing it to switch. The SFH485-2 is a good emitting diode to use with this photodiode. The pair operates at about 880/850nm, which is the sort of wavelength that even the best IR night vision cameras cannot see; so daylight is not really a problem.

If you?re worried about repeat firings accumulating heat and causing false readings, you?re worrying about the wrong thing!!!! Laying a new line of BP on a hot guide is potentially suicide, if not, definitely a loose all your hair idea, and probably skin!!! You should always let the guide cool, or use a new one; to avoid accidents/injuries. By being sensible, there wouldn?t be any heat building up anyway.

Interesting electronic detail, as I've probably mentioned, my experience is limited to repairing motorcycle looms and occasional appliance breakdowns.

Don't worry, when I was speculating about spurious heat readings I was thinking of relatively low temps, not adding BP to smoking mortars.

Another idle idea, to give an exact reading very simply why not put aluminium (or copper) tape on the side of the shell, to meet up with similar in the mortar creating a switch.
As it leaves the circuit is instantly broken.

Simon

[Andrew]

I was thinking, I don't know if this has been suggested before, but does anyone else thing that the following is a good idea?

A bit of very accurate standardised kit gets sent round all the people that want to join the quest for the fastest BP. When one person has finished with the burn rate tester, they say so and the next address gets sent to them. The next person gets it and so on; a bit of a chain competition if you will. There would obviously be rules and the tests would be standardised. Each individual person?s method of manufacture would be carefully documented with a standard form downloadable from somewhere to fill in. It would lead to a bit of armature research on mass. Everyone would enter their test results and a bit of a league table could be done. Obviously the amount of BP you would need to fill the device would be less than 100g to make sure no one gets buggered by MSER and cannot enter. Each person would be responsible for shipping it to the next, and so on, la de la la. Perhaps a bit of a competition incentive could be thrown in. To ensure no cheating occurs, well that?s complicated and I cannot think of everything!!

Any thoughts???

Would anyone enter? PM me if you would be interested, if enough people are I would not mind organising it.

[Nerro]

Just out of curiosity, did any of you ever consider milling their BP for an insanely long amount of time? Say, 100 days or something. And how fast would the BP be when it's done?

[sizzle]

Just out of curiosity, did any of you ever consider milling their BP for an insanely long amount of time? Say, 100 days or something. And how fast would the BP be when it's done?

100 days! that's four months! surely when you opened the jar it'd all float out into the air.

[Nerro]

Hold a (non-static) plastic bag over it as you open it.

After pressing and corning how good do you think it'd be? Would the loss of volatiles decrease performance or would the increased degree of mixing outway that?