Post by thread:[EE]: Phototransistors (*holding my head in shame*

> -----Original Message----- > From: Marc Nicholas [SMTP:spam_OUTmarcTakeThisOuTGEEKYTHINGS.COM] > Sent: Tuesday, July 08, 2003 1:39 PM > To: .....PICLISTKILLspam@spam@MITVMA.MIT.EDU > Subject: [EE]: Phototransistors (*holding my head in shame*) > > This is probably a really, really dumb question...and probably a result of > my lack of formal electronics education ;-) > > Why do three pin phototransistors exist? Is it purely for > aesthetics/standardized packaging reasons, or is there some intrinsic, > magical reason I'm missing? > > -marc > For biasing to improve either sensitivity or speed. Phototransistors used without any base connection are very slow. By providing a dc path from the base, the charge in the BE junction can be removed more quickly, speeding up the transistor at the cost of reducing sensitivity. Mike ======================================================================= This e-mail is intended for the person it is addressed to only. The information contained in it may be confidential and/or protected by law. If you are not the intended recipient of this message, you must not make any use of this information, or copy or show it to any person. Please contact us immediately to tell us that you have received this e-mail, and return the original to us. Any use, forwarding, printing or copying of this message is strictly prohibited. No part of this message can be considered a request for goods or services. ======================================================================= Any questions about Bookham's E-Mail service should be directed to postmasterKILLspambookham.com. -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

>So I'm fine to use a 3-pin version in a circuit that would normally use a >2-pin version...as long as I leave base N/C? No, I don't think that would be wise. You'd pick up all kinds of environmental noise on that pin, which would impact the biasing making it more or less sensitive at random. You would probably be better tying it to ground; I'm not positive about that, though. Mike H. _________________________________________________________________ The new MSN 8: smart spam protection and 2 months FREE* http://join.msn.com/?page=features/junkmail -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

Might be better to acquire a 2-pin phototransistor, then ;-) -marc On 8/7/03 11:24, "Mike Hord" <gaidinmdspam_OUTHOTMAIL.COM> wrote: {Quote hidden}>> So I'm fine to use a 3-pin version in a circuit that would normally use a >> 2-pin version...as long as I leave base N/C? > > No, I don't think that would be wise. You'd pick up all kinds of > environmental noise on that pin, which would impact the biasing > making it more or less sensitive at random. You would probably > be better tying it to ground; I'm not positive about that, though. > > Mike H. > > _________________________________________________________________ > The new MSN 8: smart spam protection and 2 months FREE* > http://join.msn.com/?page=features/junkmail > > -- > http://www.piclist.com hint: The PICList is archived three different > ways. See http://www.piclist.com/#archives for details. > -------------------------------------------------- Marc Nicholas Geekythings Inc. C/416.543.4896 UNIX, Database, Security and Networking Consulting -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

On 8/7/03 10:59, "Mike Singer" <@spam@msingerKILLspamPOLUOSTROV.NET> wrote: >> If it had two pins it would be called a photo diode... > > 2-pin phototransistors were more common than 3-pin in my > experience. I concur with that...I've only ever dealt with the 2-pin variety before, which is why the 3-pin variety kinda had me wondering. -marc -------------------------------------------------- Marc Nicholas Geekythings Inc. C/416.543.4896 UNIX, Database, Security and Networking Consulting -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

I woud expect it to work if you tie the base back to the collector supply through a 100k resistor. That may provide too much gain for a circuit intended for a diode. John Ferrell 6241 Phillippi Rd Julian NC 27283 Phone: (336)685-9606 KILLspamjohnferrellKILLspamearthlink.net Dixie Competition Products NSRCA 479 AMA 4190 W8CCW "My Competition is Not My Enemy" ----- Original Message ----- From: "Marc Nicholas" <RemoveMEmarcTakeThisOuTGEEKYTHINGS.COM> To: <spamBeGonePICLISTspamBeGoneMITVMA.MIT.EDU> Sent: Tuesday, July 08, 2003 9:18 AM Subject: Re: [EE]: Phototransistors (*holding my head in shame*) > That actually makes complete sense! :-) > > So I'm fine to use a 3-pin version in a circuit that would normally use a > 2-pin version...as long as I leave base N/C? > > -marc > > On 8/7/03 08:47, "Michael Rigby-Jones" <TakeThisOuTMichael.Rigby-JonesEraseMEspam_OUTBOOKHAM.COM> > wrote: > > >> {Original Message removed}

>>> If it had two pins it would be called a photo diode... >> >> 2-pin phototransistors were more common than 3-pin in my >> experience. > >I concur with that...I've only ever dealt with the 2-pin variety before, >which is why the 3-pin variety kinda had me wondering. Hehe. 3-pin phototransistors were the most common in hobbyist times because that's what you set if you carefully saw off the top of a metal can transistor like 2N2222 ;-) Peter -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email RemoveMElistservEraseMEEraseMEmitvma.mit.edu with SET PICList DIGEST in the body

I had not heard of the the EPROM bit, Please enlighten me. I have used a LED as a photodiode. John Ferrell 6241 Phillippi Rd Julian NC 27283 Phone: (336)685-9606 RemoveMEjohnferrellTakeThisOuTspamearthlink.net Dixie Competition Products NSRCA 479 AMA 4190 W8CCW "My Competition is Not My Enemy" ----- Original Message ----- From: "Marc Nicholas" <EraseMEmarcspamspamBeGoneGEEKYTHINGS.COM> To: <RemoveMEPICLISTKILLspamMITVMA.MIT.EDU> Sent: Wednesday, July 09, 2003 3:28 PM Subject: Re: [EE]: Phototransistors (*holding my head in shame*) {Quote hidden}> Shades of using EPROMs as crude input devices ;-) > > > -marc > > On 9/7/03 15:10, "Steve Smith" <xygaxSTOPspamspam_OUTBLUEYONDER.CO.UK> wrote: > > > A more simple soulition than sawing the top off :- > > OC71 scrape the paint off and you have an OCP71 > > > > (maybe 30 years ago) > > > > Steve...... > > > > {Original Message removed}

Actually, maybe it was ROM chips...but, anyways, back in ceramic casing days you could file away the casing and make a crude imaging array. -marc On 9/7/03 15:56, "John Ferrell" <spamBeGonejohnferrellSTOPspamEraseMEEARTHLINK.NET> wrote: {Quote hidden}> I had not heard of the the EPROM bit, Please enlighten me. > > I have used a LED as a photodiode. > > John Ferrell > 6241 Phillippi Rd > Julian NC 27283 > Phone: (336)685-9606 > KILLspamjohnferrellspamBeGoneearthlink.net > Dixie Competition Products > NSRCA 479 AMA 4190 W8CCW > "My Competition is Not My Enemy" > > ----- Original Message ----- > From: "Marc Nicholas" <EraseMEmarcEraseMEGEEKYTHINGS.COM> > To: <@spam@PICLIST@spam@spam_OUTMITVMA.MIT.EDU> > Sent: Wednesday, July 09, 2003 3:28 PM > Subject: Re: [EE]: Phototransistors (*holding my head in shame*) > > >> Shades of using EPROMs as crude input devices ;-) >> >> >> -marc >> >> On 9/7/03 15:10, "Steve Smith" <spamBeGonexygaxKILLspamBLUEYONDER.CO.UK> wrote: >> >>> A more simple soulition than sawing the top off :- >>> OC71 scrape the paint off and you have an OCP71 >>> >>> (maybe 30 years ago) >>> >>> Steve...... >>> >>> {Original Message removed}

> Actually, maybe it was ROM chips...but, anyways, back in ceramic casing > days you could file away the casing and make a crude imaging array. Dr. William Yerazunis of the Mitsubishi research center in Cambridge Massachusetts has used this concept to develop a low cost imaging array from dynamic RAM circuits. These things are now in production and are used as cheap image arrays in toys and low end devices. They also have an exponential response, which is useful in dealing with the large dynamic range of brightness the human eye can interpret. ***************************************************************** Embed Inc, embedded system specialists in Littleton Massachusetts (978) 742-9014, http://www.embedinc.com -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email .....listservspam_OUTmitvma.mit.edu with SET PICList DIGEST in the body

> Actually, maybe it was ROM chips...but, anyways, back in > ceramic casing > days you could file away the casing and make a crude imaging array. IIRC this was described in a Circuit Cellar article long long ago, when Byte was still the leading computer magazine. Wouter van Ooijen -- ------------------------------------------- Van Ooijen Technische Informatica: http://www.voti.nl consultancy, development, PICmicro products -- http://www.piclist.com hint: To leave the PICList TakeThisOuTpiclist-unsubscribe-requestKILLspamspammitvma.mit.edu>

> -----Original Message----- > From: Mike Hord [SMTP:.....gaidinmdRemoveMEHOTMAIL.COM] > Sent: Tuesday, July 08, 2003 4:25 PM > To: RemoveMEPICLISTspamBeGoneMITVMA.MIT.EDU > Subject: Re: [EE]: Phototransistors (*holding my head in shame*) > > >So I'm fine to use a 3-pin version in a circuit that would normally use a > >2-pin version...as long as I leave base N/C? > > No, I don't think that would be wise. You'd pick up all kinds of > environmental noise on that pin, which would impact the biasing > making it more or less sensitive at random. You would probably > be better tying it to ground; I'm not positive about that, though. > > Mike H. > Tying the base to ground would stop the transistor ever switching on! The OP's circuit will probably work fine with the base open, but if it's operating in a noisy environment, it may be better to try and source a part without the base connection. Mike ======================================================================= This e-mail is intended for the person it is addressed to only. The information contained in it may be confidential and/or protected by law. If you are not the intended recipient of this message, you must not make any use of this information, or copy or show it to any person. Please contact us immediately to tell us that you have received this e-mail, and return the original to us. Any use, forwarding, printing or copying of this message is strictly prohibited. No part of this message can be considered a request for goods or services. ======================================================================= Any questions about Bookham's E-Mail service should be directed to spamBeGonepostmaster@spam@spam_OUTbookham.com. -- http://www.piclist.com hint: To leave the PICList TakeThisOuTpiclist-unsubscribe-requestspammitvma.mit.edu>

No, it was early dynamic RAM chips. The charge in the memory cells leaks off more quickly when exposed to light. Early DRAM chips had a refresh cycle that was separate from the read cycle. You'd write all 1's to the chip, then repeatedly read the array without refresh. The cells that changed to 0's first had the highest brightness. Byte Magazine even had a construction article and code to make a simple B&W imager, long before CCD's or web cams existed. members.tripod.com/RoBoJRR/techcorner.htm "The September and October 83 issues of Byte Magazine contain an in depth article on building a camera based on Micron's OpticRam. Technology guru, Steve Ciarcia, provides not only a highly detailed description of the technology involved, but complete schematics and software listings as well. This fine article is included in his Circuit Cellar Inc. series as well and may be easier to find than the original Byte articles." Marc Nicholas wrote: {Quote hidden}> > Actually, maybe it was ROM chips...but, anyways, back in ceramic casing days > you could file away the casing and make a crude imaging array. > > -marc > > On 9/7/03 15:56, "John Ferrell" <johnferrellEraseMEEARTHLINK.NET> wrote: > > > I had not heard of the the EPROM bit, Please enlighten me. > > > > I have used a LED as a photodiode. Oops, you just infringed an AT&T patent. Seems that a Popular (Radio?) Electronics columnist wrote in the late 70's an article about doing exactly that, to experiment with bidirectional communication over the 'new' optical fibre technology. AT&T lawyers showed up with the police to execute a search warrant on his home, claiming that he must have committed industrial espionage in order for him to have written about their yet to be obtained patent. The columnist was so pissed off that he dedicated half his column to slamming their strong arm tactics. I think it was Don Lancaster, but I'm not certain. R {Quote hidden}> > ----- Original Message ----- > > From: "Marc Nicholas" <RemoveMEmarcEraseMEspam_OUTGEEKYTHINGS.COM> > > To: <@spam@PICLISTRemoveMEEraseMEMITVMA.MIT.EDU> > > Sent: Wednesday, July 09, 2003 3:28 PM > > Subject: Re: [EE]: Phototransistors (*holding my head in shame*) > >> Shades of using EPROMs as crude input devices ;-) > >> -marc > >> > >> On 9/7/03 15:10, "Steve Smith" <EraseMExygax@spam@BLUEYONDER.CO.UK> wrote: > >> > >>> A more simple soulition than sawing the top off :- > >>> OC71 scrape the paint off and you have an OCP71 > >>> > >>> (maybe 30 years ago) > >>> > >>> Steve...... > >>> > >>> {Original Message removed}

At 01:36 AM 7/10/03 -0600, Robert Rolf wrote: >Oops, you just infringed an AT&T patent. > >Seems that a Popular (Radio?) Electronics columnist wrote in the late 70's >an article about doing exactly that, >to experiment with bidirectional communication over the 'new' >optical fibre technology. > >AT&T lawyers showed up with the police to execute a search warrant on >his home, claiming that he must have committed industrial espionage in >order for him to have written about their yet to be obtained patent. >The columnist was so pissed off that he dedicated half his column to slamming >their strong arm tactics. I think it was Don Lancaster, but I'm not certain. Actually, it was Forrest W Mimms III. Many will recognize the name from his "Engineer's Notebook" series often seen at Radio Shack. dwayne -- Dwayne Reid <dwaynerspamBeGoneplanet.eon.net> Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax Celebrating 19 years of Engineering Innovation (1984 - 2003) .-. .-. .-. .-. .-. .-. .-. .-. .-. .- `-' `-' `-' `-' `-' `-' `-' `-' `-' Do NOT send unsolicited commercial email to this email address. This message neither grants consent to receive unsolicited commercial email nor is intended to solicit commercial email. -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

On 11/7/03 15:38, "Dwayne Reid" <RemoveMEdwayner@spam@spamBeGonePLANET.EON.NET> wrote: >> AT&T lawyers showed up with the police to execute a search warrant on >> his home, claiming that he must have committed industrial espionage in >> order for him to have written about their yet to be obtained patent. >> The columnist was so pissed off that he dedicated half his column to slamming >> their strong arm tactics. I think it was Don Lancaster, but I'm not certain. > > Actually, it was Forrest W Mimms III. Many will recognize the name from > his "Engineer's Notebook" series often seen at Radio Shack. Yeah, I have some of his booklets!!! Memories of when Radioshack actually sold some worthwhile products ;-) -marc -------------------------------------------------- Marc Nicholas Geekythings Inc. C/416.543.4896 UNIX, Database, Security and Networking Consulting -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

At 01:36 AM 7/10/03 -0600, Robert Rolf wrote: >Oops, you just infringed an AT&T patent. > >Seems that a Popular (Radio?) Electronics columnist wrote in the late 70's >an article about doing exactly that, >to experiment with bidirectional communication over the 'new' >optical fibre technology. > >AT&T lawyers showed up with the police to execute a search warrant on >his home, claiming that he must have committed industrial espionage in >order for him to have written about their yet to be obtained patent. >The columnist was so pissed off that he dedicated half his column to slamming >their strong arm tactics. I think it was Don Lancaster, but I'm not certain. Actually, it was Forrest W Mimms III. Many will recognize the name from his "Engineer's Notebook" series often seen at Radio Shack. dwayne -- Dwayne Reid <.....dwayner@spam@EraseMEplanet.eon.net> Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax Celebrating 19 years of Engineering Innovation (1984 - 2003) .-. .-. .-. .-. .-. .-. .-. .-. .-. .- `-' `-' `-' `-' `-' `-' `-' `-' `-' Do NOT send unsolicited commercial email to this email address. This message neither grants consent to receive unsolicited commercial email nor is intended to solicit commercial email. -- http://www.piclist.com hint: To leave the PICList .....piclist-unsubscribe-requestRemoveMEmitvma.mit.edu>