Post by thread:[EE]: Rocket Project

Hi all, Just a quick update on the progress of the rocket project recently discussed here under the heading: "Noise in phototransistors". First off, I made a new circuit which has a couple of amplification stages and a 4-pole butterworth high pass filter (to eliminate 60/120 Hz light sources while passing the ~2.5kHz carrier properly). Using a PNZ330CL PIN photodiode, my tests show that the noise delivered by this circuit is close to the best it can be (on the order of 50 pA in the photodiode, while shot noise from the current caused by ambient light would cause about 25 pA in the roughly 1kHz BW which it currently has). I am also using a 37 mm lens now and it has greatly improved the sensitivity, thanks! The source is easily detectible in a 1kHz BW in headphones at >100 feet (I didn't test further) and with the addition of the narrow digital band pass filter in the PIC, the noise should be decreased by about a factor of 5 or so (final BW will ony be about 20Hz). I found out that a large percentage of my noise I was seeing before was due to 60Hz (and harmonics) pickup at several high-impedance points in the circuit. I reduced the resistor values and increased the corresponding capacitor values (these points were in the filters). The phototransistor does seem to have several times the noise level of the photodiode, too. I have also ordered some IR transparent, visible light blocking plastic to reduce the effects of ambient light on the sensor (hoping to reduce DC current in photodiode). Currently, taking it outside on a bright sunny day saturates the first stage, so I may have to reduce the transimpedance gain if the plastic doesn't do the trick. I also made a matlab-based simulation including ballistic and aerodynamic effects, and a simple control scheme. It appears from this simulation that my servos will be plenty fast, given that I have a non-moving target and will only have about a +/- 15 deg FOV anyway. One last thing: Dave or anyone else, where can I find out if this really is disallowed (for sure) under NAR rules(Honestly, I am not trying to hit the target, only use an air-suspended device to guide a model rocket near to it, and I plan on adjusting the null zone and control authority to try to prevent a direct hit)? I was planning on testing this out at a local RC flying field, but I just realized that the Sportflyer's (I think that's the group he's with) rules may not allow this if it doesn't comply with the NAR(like the AMA), and I don't want to cause insurance problems. (He was kind enough to say I could launch rockets there, but this might be pushing it ;-) Once again, standard disclaimer, if you are wondering what this is about, read the previous thread, it is a simple model rocketry project to guide a model rocket near some balloons, it is NOT an anti-aircraft missile. (I always append this lest someone read one of these messages in the archives). | | Sean Breheny | Amateur Radio Callsign: KA3YXM | Electrical Engineering Student \--------------=---------------- Save lives, please look at http://www.all.org Personal page: http://www.people.cornell.edu/pages/shb7 spam_OUTshb7TakeThisOuTcornell.edu ICQ #: 3329174 ____________NetZero Free Internet Access and Email_________ Download Now http://www.netzero.net/download/index.html Request a CDROM 1-800-333-3633 ___________________________________________________________

Hi all. I recently designed a robot for a contest in France. (http://eurobot.win.tue.nl) The robot found it's way by means of Infra-red beacons. As the match was filmed on TV, I had to design something that was immune for ambient light influences. The result was, that the modulated signal (1 - 5 KHz) was clearly measurable, even when a 500-W halogen lamp was pointed at the IR-receivers at a distance of .5 metres. The circuit used for detection consists of a couple of transistors and capacitors to simulate an inductance. If someone has interest, I could send a pdf of the schematic. As far as the plastic concerns : Farnell (http://www.farnell.com) had IR-lenses from that type of plastic. Though I have to say the solution I used works better than those lenses. Cya. Hans On Thu, Jun 29, 2000 at 10:47:35AM +0100, Andrew Seddon wrote: > Hi. > Could you tell me where you got that visible light blocking plastic that > lets IR thorugh from please? That could come in usefull in what I am about > to do. > > Cheers.. > > Andrew Seddon >

Two ways - The cheapest IR filter is a fiece of exposed 35mm film. Just get one of the negatives from those "scenic lens caps" that people always take, and tell your photo lab to develop it anyway. Or just ask them for one- they thrown them away. The next level is an actual IR filter from a good phot shop. These screw onto a regular camera lens, and are used for taking IR pictures with special film and a standard camera. They look coal black, but are IR clear. ~ $25. -----Original Message----- From: Andrew Seddon <.....seddonaKILLspam@spam@HOTMAIL.COM> To: PICLISTKILLspamMITVMA.MIT.EDU <.....PICLISTKILLspam.....MITVMA.MIT.EDU> Date: Thursday, June 29, 2000 4:53 AM Subject: [EE]: Rocket Project >Hi. > Could you tell me where you got that visible light blocking plastic that >lets IR thorugh from please? That could come in usefull in what I am about >to do. > >Cheers.. > >Andrew Seddon

Sean, I'm not an expert wit modle rockets, but the QRA has NO religious guidleine on active control, however in Australia the "wise word" for us was "No active control during the thrust phase", control during coasting, or recovery is acceptable. Apparently this guideline is based on the instructions from the Estes Astroblaster, Sweet vee, and the other RC BG. Maybe you should get the guidlelines/regs for RC BG/RG and see what they say... I really think this will be the closest you're going to find about guidance under thrust. Hope this helps, Des Bromilow Fulltime Engineer, Part time fixer-upper, Rocket builder, QRA President, and general dogsbody. >>> Sean Breheny <shb7spam_OUTCORNELL.EDU> 6/29/00 2:13:32 pm >>> Hi all, Just a quick update on the progress of the rocket project recently discussed here under the heading: "Noise in phototransistors". First off, I made a new circuit which has a couple of amplification stages and a 4-pole butterworth high pass filter (to eliminate 60/120 Hz light sources while passing the ~2.5kHz carrier properly). Using a PNZ330CL PIN photodiode, my tests show that the noise delivered by this circuit is close to the best it can be (on the order of 50 pA in the photodiode, while shot noise from the current caused by ambient light would cause about 25 pA in the roughly 1kHz BW which it currently has). I am also using a 37 mm lens now and it has greatly improved the sensitivity, thanks! The source is easily detectible in a 1kHz BW in headphones at >100 feet (I didn't test further) and with the addition of the narrow digital band pass filter in the PIC, the noise should be decreased by about a factor of 5 or so (final BW will ony be about 20Hz). I found out that a large percentage of my noise I was seeing before was due to 60Hz (and harmonics) pickup at several high-impedance points in the circuit. I reduced the resistor values and increased the corresponding capacitor values (these points were in the filters). The phototransistor does seem to have several times the noise level of the photodiode, too. I have also ordered some IR transparent, visible light blocking plastic to reduce the effects of ambient light on the sensor (hoping to reduce DC current in photodiode). Currently, taking it outside on a bright sunny day saturates the first stage, so I may have to reduce the transimpedance gain if the plastic doesn't do the trick. I also made a matlab-based simulation including ballistic and aerodynamic effects, and a simple control scheme. It appears from this simulation that my servos will be plenty fast, given that I have a non-moving target and will only have about a +/- 15 deg FOV anyway. One last thing: Dave or anyone else, where can I find out if this really is disallowed (for sure) under NAR rules(Honestly, I am not trying to hit the target, only use an air-suspended device to guide a model rocket near to it, and I plan on adjusting the null zone and control authority to try to prevent a direct hit)? I was planning on testing this out at a local RC flying field, but I just realized that the Sportflyer's (I think that's the group he's with) rules may not allow this if it doesn't comply with the NAR(like the AMA), and I don't want to cause insurance problems. (He was kind enough to say I could launch rockets there, but this might be pushing it ;-) Once again, standard disclaimer, if you are wondering what this is about, read the previous thread, it is a simple model rocketry project to guide a model rocket near some balloons, it is NOT an anti-aircraft missile. (I always append this lest someone read one of these messages in the archives). | | Sean Breheny | Amateur Radio Callsign: KA3YXM | Electrical Engineering Student \--------------=---------------- Save lives, please look at http://www.all.org Personal page: http://www.people.cornell.edu/pages/shb7 @spam@shb7KILLspamcornell.edu ICQ #: 3329174 ____________NetZero Free Internet Access and Email_________ Download Now http://www.netzero.net/download/index.html Request a CDROM 1-800-333-3633 ___________________________________________________________

"Robert A. LaBudde" wrote: > > At 10:47 AM 6/29/00 +0100, Andrew wrote: > >Hi. > > Could you tell me where you got that visible light blocking plastic that > >lets IR thorugh from please? That could come in usefull in what I am about > >to do. > > Exposed (fogged) photographic film is the standard IR filter. Just point > the camera at the sky to over expose it. Than use a piece of the developed > negative to block visible light and pass IR. > > ================================================================ > Robert A. LaBudde, PhD, PAS, Dpl. ACAFS e-mail: KILLspamralKILLspamlcfltd.com > Least Cost Formulations, Ltd. URL: http://lcfltd.com/ > 824 Timberlake Drive Tel: 757-467-0954 > Virginia Beach, VA 23464-3239 Fax: 757-467-2947 > > "Vere scire est per causas scire" > ================================================================ or just yank the film out of the roll.. in the daylight.. and then wind it back up by hand.. that way you don't get the frame marks every 35mm just one blank roll.. get some CHEAP film.. like a 10-12shot of 100 speed film for like 99 cents. make sure you tell the film shop it's supposed to be that way and to not cut the negatives and don't bother to print it.. at a Ritz Camera or Wolf around here it's only like $3 to get the negatives developed..

B&W or color? Andy Damon Hopkins <RemoveMEmdhopkinTakeThisOuTUNITY.NCSU.EDU> on 06/30/2000 02:03:28 AM Please respond to pic microcontroller discussion list <spamBeGonePICLISTspamBeGoneMITVMA.MIT.EDU> To: TakeThisOuTPICLISTEraseMEspam_OUTMITVMA.MIT.EDU cc: (bcc: Andrew Kunz/TDI_NOTES) Subject: Re: [EE]: Rocket Project "Robert A. LaBudde" wrote: {Quote hidden}> > At 10:47 AM 6/29/00 +0100, Andrew wrote: > >Hi. > > Could you tell me where you got that visible light blocking plastic that > >lets IR thorugh from please? That could come in usefull in what I am about > >to do. > > Exposed (fogged) photographic film is the standard IR filter. Just point > the camera at the sky to over expose it. Than use a piece of the developed > negative to block visible light and pass IR. > > ================================================================ > Robert A. LaBudde, PhD, PAS, Dpl. ACAFS e-mail: RemoveMEralTakeThisOuTlcfltd.com > Least Cost Formulations, Ltd. URL: http://lcfltd.com/ > 824 Timberlake Drive Tel: 757-467-0954 > Virginia Beach, VA 23464-3239 Fax: 757-467-2947 > > "Vere scire est per causas scire" > ================================================================ or just yank the film out of the roll.. in the daylight.. and then wind it back up by hand.. that way you don't get the frame marks every 35mm just one blank roll.. get some CHEAP film.. like a 10-12shot of 100 speed film for like 99 cents. make sure you tell the film shop it's supposed to be that way and to not cut the negatives and don't bother to print it.. at a Ritz Camera or Wolf around here it's only like $3 to get the negatives developed..

Andrew Kunz wrote: > > B&W or color? You know .. it's funny that for as much as I know about film I have no idea.. I took for granted what the other poster said about just using exposed film.. I'd guess color as color film has separate layers w/ dyes in it that are reactive to different spectrums of light (cyan,magenta,yellow) also it's cheaper to develop as most film labs can process it in house.. I'd suggest lower speed film as it contains finer particles of silver (bigger particles would mean more light blockage i.e. most sensitive to light in regular usage) it's also cheaper. I'll pass this by my father who knows just about everything.. he used to make his own photo chemicals and paper when my mother was a photographer.. he'll probably know.. Damon Hopkins -- /-=-=-=-=-=-=-=-=-=-=-=-=-\ | http://www.openpic.com | | New OpenSource Pic site | \-=-=-=-=-=-=-=-==-=-==-=-/

>>> exposed film as IR filter >> B&W or color? > I took for granted what the other poster said about just using > exposed film.. I'd guess color as color film has separate layers > w/ dyes in it that are reactive to different spectrums of light > (cyan,magenta,yellow) I believe you want exposed & developed color negative film or unexposed & developer color reversal film (i.e. slide film). Color negative film will have an orange tint. Slide film will have a black look. Checking a Kodak data book on color films, the cyan layer's spectral response curve falls off at 700nm. IR at 800nm or so should pass quite well. Black & white isn't as easy a question as expected. There's the old style films, like Kodak Tri-X, based on silver granules. Those, when exposed and developed, should have a fairly flat spectral response curve. I would expect they would attenuate IR wavelengths as well as visible light. There are also black & white emulsions based on color film technology, such as Kodak's T-Max. I have no idea how they would respond as an IR filter. Lee Jones

At 01:49 AM 7/1/00 -0400, Damon wrote: >Andrew Kunz wrote: > > > > B&W or color? >You know .. it's funny that for as much as I know about film I have no >idea.. >I took for granted what the other poster said about just using exposed >film.. I'd guess color as color film has separate layers w/ dyes in it >that are reactive to different spectrums of light (cyan,magenta,yellow) >also it's cheaper to develop as most film labs can process it in house.. >I'd suggest lower speed film as it contains finer particles of silver >(bigger particles would mean more light blockage i.e. most sensitive to >light in regular usage) it's also cheaper. >I'll pass this by my father who knows just about everything.. he used to >make his own photo chemicals and paper when my mother was a >photographer.. he'll probably know.. Black and white is much more predictable. ================================================================ Robert A. LaBudde, PhD, PAS, Dpl. ACAFS e-mail: ralEraseME.....lcfltd.com Least Cost Formulations, Ltd. URL: http://lcfltd.com/ 824 Timberlake Drive Tel: 757-467-0954 Virginia Beach, VA 23464-3239 Fax: 757-467-2947 "Vere scire est per causas scire" ================================================================

Andrew Kunz wrote: {Quote hidden}> > B&W or color? > > Andy > > Damon Hopkins <EraseMEmdhopkinUNITY.NCSU.EDU> on 06/30/2000 02:03:28 AM > > Please respond to pic microcontroller discussion list <RemoveMEPICLISTEraseMEEraseMEMITVMA.MIT.EDU> > > To: RemoveMEPICLISTspam_OUTKILLspamMITVMA.MIT.EDU > > cc: (bcc: Andrew Kunz/TDI_NOTES) > > Subject: Re: [EE]: Rocket Project > > "Robert A. LaBudde" wrote: > > > > At 10:47 AM 6/29/00 +0100, Andrew wrote: > > >Hi. > > > Could you tell me where you got that visible light blocking plastic that > > >lets IR thorugh from please? That could come in usefull in what I am about > > >to do. > > > > Exposed (fogged) photographic film is the standard IR filter. Just point > > the camera at the sky to over expose it. Than use a piece of the developed > > negative to block visible light and pass IR. > > > > ================================================================ > > Robert A. LaBudde, PhD, PAS, Dpl. ACAFS e-mail: RemoveMEralTakeThisOuTspamlcfltd.com > > Least Cost Formulations, Ltd. URL: http://lcfltd.com/ > > 824 Timberlake Drive Tel: 757-467-0954 > > Virginia Beach, VA 23464-3239 Fax: 757-467-2947 > > > > "Vere scire est per causas scire" > > ================================================================ > > or just yank the film out of the roll.. in the daylight.. and then wind > it back up by hand.. that way you don't get the frame marks every 35mm > just one blank roll.. get some CHEAP film.. like a 10-12shot of 100 > speed film for like 99 cents. make sure you tell the film shop it's > supposed to be that way and to not cut the negatives and don't bother to > print it.. > > at a Ritz Camera or Wolf around here it's only like $3 to get the > negatives developed.. I talked to my dad. he works at Honeywell and ALOT of what they do is with IR stuff.. he said what they use is called polysulfone from GE. I believe he said get some Udel P-1700 and tell them you want it to block visible light but not IR.. it should be dark purple and he said he believed you could get a sample of it. it blocks about 90% of visible light and lets about 90% of the IR spectrum through. also he said that color any film will just end up being a neutral filter and block out infrared as well as visible. Damon Hopkins -- /-=-=-=-=-=-=-=-=-=-=-=-=-\ | http://www.openpic.com | | New OpenSource Pic site | \-=-=-=-=-=-=-=-==-=-==-=-/ -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

Hi all, Sorry it took me so long to respond to the original question. The IR blocking plastic I got was from Edmund Scientific's Industrial Optics division, part number K43-949 (for a 2" diameter disc). It is available in various sizes but is expensize, $7.00 for the 2" disc. It also didn't do the trick in my case, apparently because there is so much IR in daylight anyway. Sean | | Sean Breheny | Amateur Radio Callsign: KA3YXM | Electrical Engineering Student \--------------=---------------- Save lives, please look at http://www.all.org Personal page: http://www.people.cornell.edu/pages/shb7 EraseMEshb7spamspamBeGonecornell.edu ICQ #: 3329174 ____________NetZero Free Internet Access and Email_________ Download Now http://www.netzero.net/download/index.html Request a CDROM 1-800-333-3633 ___________________________________________________________ -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

Dear Hans, I would be interested in the PDF of that schematic. Thanks, Sean At 05:37 PM 6/29/00 +0200, H.P. de Vries wrote: {Quote hidden}>Hi all. > >I recently designed a robot for a contest in France. >(http://eurobot.win.tue.nl) >The robot found it's >way by means of Infra-red beacons. As the match was filmed on TV, I had to >design something that was immune for ambient light influences. The result >was, that the modulated signal (1 - 5 KHz) was clearly measurable, even when >a 500-W halogen lamp was pointed at the IR-receivers at a distance of .5 >metres. The circuit used for detection consists of a couple of transistors >and capacitors to simulate an inductance. >If someone has interest, I could send a pdf of the schematic. As far as the >plastic concerns : >Farnell (http://www.farnell.com) had IR-lenses from that type of plastic. Though I >have to say the solution I used works better than those lenses. > >Cya. > >Hans > >On Thu, Jun 29, 2000 at 10:47:35AM +0100, Andrew Seddon wrote: >> Hi. >> Could you tell me where you got that visible light blocking plastic that >> lets IR thorugh from please? That could come in usefull in what I am about >> to do. >> >> Cheers.. >> >> Andrew Seddon >> > | | Sean Breheny | Amateur Radio Callsign: KA3YXM | Electrical Engineering Student \--------------=---------------- Save lives, please look at http://www.all.org Personal page: http://www.people.cornell.edu/pages/shb7 RemoveMEshb7KILLspamcornell.edu ICQ #: 3329174 ____________NetZero Free Internet Access and Email_________ Download Now http://www.netzero.net/download/index.html Request a CDROM 1-800-333-3633 ___________________________________________________________ -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.