Post by thread:[EE]: looking for retriggerable 555 monostable cir

You're looking for a retriggerable one shot, AKA "Missing pulse detector" I've seen 555 ckts to do this, check an older National semi data book On 3/30/06, Rob Robson <spam_OUTrobTakeThisOuTsilk.net> wrote: {Quote hidden}> > I'm looking for a 555-based monostable (one-shot) circuit whose output > will > STAY high as long as short negative-going pulses are present at the input. > The textbook 555 monostable circuit doesn't do this. I have a spare NPN > on > the board to utilize if necessary. Has anyone come across a 555 circuit > that will do this? > > Many thanks, > RR > > > -

I'd do it with a PIC10F20X. It would be 1/10 size, cost 1/5 as much, and would be more reliable than a 555. Take about 5 minutes to write this code. --Bob David VanHorn wrote: {Quote hidden}>You're looking for a retriggerable one shot, AKA "Missing pulse detector" >I've seen 555 ckts to do this, check an older National semi data book > > > >On 3/30/06, Rob Robson <.....robKILLspam@spam@silk.net> wrote: > > >>I'm looking for a 555-based monostable (one-shot) circuit whose output >>will >>STAY high as long as short negative-going pulses are present at the input. >>The textbook 555 monostable circuit doesn't do this. I have a spare NPN >>on >>the board to utilize if necessary. Has anyone come across a 555 circuit >>that will do this? >> >>Many thanks, >>RR >> >> >>-

On Mar 30, 2006, at 9:29 AM, Rob Robson wrote: > I'm looking for a 555-based monostable (one-shot) circuit whose > output will STAY high as long as short negative-going pulses are > present at the input. The textbook 555 monostable circuit doesn't > do this. I have a spare NPN on the board to utilize if > necessary. Has anyone come across a 555 circuit that will do this? > Google for "555 missing pulse detector" and you'll turn up a standard schematic. It uses an external PNP transistor to discharge the cap... BillW

The problem is that I'm trying to fix a circuit that's already been committed to PCB with the least ugly kludge possible. It's like the Apollo 13 problem: trying to turn what you have into what you need. What I have is a 555 one-shot and an extra NPN transistor. What I need is a retriggerable one-shot whose output goes high and stays high when the input receives negative-going pulses, then goes low again once the pulses have been gone for a second or two. I'm looking at the inner workings of the 555 to try to come up with a clever way to do this, but I'm running out of cleverness. I don't have access printed resources at the moment, and my Googling has yet to expose a solution. I'd be very grateful if anyone who has come across a circuit that fits this description could pass it along. RR > I'd do it with a PIC10F20X. It would be 1/10 size, cost 1/5 as much, and > would be more reliable than a 555. Take about 5 minutes to write this > code. > > --Bob

> I'd do it with a PIC10F20X. It would be 1/10 size, cost 1/5 > as much dunno where you buy your 555's (or 10F's!), but I can still buy a bunch of 555's for the price of one 10F. But if you include the components around the 555 the price is probably the same. If you include the PCB area and cost of placement... (but then you'd have to include the cost of programming the 10F too). Wouter van Ooijen -- ------------------------------------------- Van Ooijen Technische Informatica: http://www.voti.nl consultancy, development, PICmicro products docent Hogeschool van Utrecht: http://www.voti.nl/hvu

Rob Robson wrote: > The problem is that I'm trying to fix a circuit that's already been > committed to PCB with the least ugly kludge possible. It's like the Apollo > 13 problem: trying to turn what you have into what you need. What I have is > a 555 one-shot and an extra NPN transistor. What I need is a retriggerable > one-shot whose output goes high and stays high when the input receives > negative-going pulses, then goes low again once the pulses have been gone > for a second or two. I'm looking at the inner workings of the 555 to try to > come up with a clever way to do this, but I'm running out of cleverness. I > don't have access printed resources at the moment, and my Googling has yet > to expose a solution. I'd be very grateful if anyone who has come across a > circuit that fits this description could pass it along. > > RR Rob, what you want is more easily found under the name of "missing pulse detector". Googling finds some similar ones: http://www.uoguelph.ca/~antoon/circ/mispulse.htm http://home.cogeco.ca/~rpaisley4/LM555.html#22

See figure 10 here: <http://www.web-ee.com/primers/files/555AN.pdf> Did that help? David Rob Robson wrote: {Quote hidden}>The problem is that I'm trying to fix a circuit that's already been >committed to PCB with the least ugly kludge possible. It's like the Apollo >13 problem: trying to turn what you have into what you need. What I have is >a 555 one-shot and an extra NPN transistor. What I need is a retriggerable >one-shot whose output goes high and stays high when the input receives >negative-going pulses, then goes low again once the pulses have been gone >for a second or two. I'm looking at the inner workings of the 555 to try to >come up with a clever way to do this, but I'm running out of cleverness. I >don't have access printed resources at the moment, and my Googling has yet >to expose a solution. I'd be very grateful if anyone who has come across a >circuit that fits this description could pass it along. > >RR > > > > > >>I'd do it with a PIC10F20X. It would be 1/10 size, cost 1/5 as much, and >>would be more reliable than a 555. Take about 5 minutes to write this >>code. >> >>--Bob >> >> > > > >

Or if the OP wants a no brainer hardware solution, 74HC221 retriggerable monostable. If he want's to do it with 555, couple the short negative going pulse into the timing cap using a diode so that the charge is pulled off for every negative pulse and so the cap never reaches 2/3 Vcc to flop the flip flop and activate 555 reset. Use the negative pulse to trigger the 555 as well (sets the flip, clearing reset and driving output high). If the input signal can't handle the cap loading, they he'll have to use the NPN to discharge the timing cap, and add another series cap and R & Diode to ground to differentiate the incoming pulse and turn the NPN on for long enough to reset the cap. Robert Bob Axtell wrote: {Quote hidden}> I'd do it with a PIC10F20X. It would be 1/10 size, cost 1/5 as much, and > would be more reliable than a 555. Take about 5 minutes to write this code. > > --Bob > > David VanHorn wrote: > > >>You're looking for a retriggerable one shot, AKA "Missing pulse detector" >>I've seen 555 ckts to do this, check an older National semi data book >> >> >> >>On 3/30/06, Rob Robson <robKILLspamsilk.net> wrote: >> >> >> >>>I'm looking for a 555-based monostable (one-shot) circuit whose output >>>will >>>STAY high as long as short negative-going pulses are present at the input. >>>The textbook 555 monostable circuit doesn't do this. I have a spare NPN >>>on >>>the board to utilize if necessary. Has anyone come across a 555 circuit >>>that will do this? >>> >>>Many thanks, >>>RR >>> >>> >>>--

Something like http://www.uoguelph.ca/~antoon/circ/mispulse.htm should work for you -----Original Message----- From: "Rob Robson" <.....robKILLspam.....silk.net> To: "Microcontroller discussion list - Public." <EraseMEpiclistspam_OUTTakeThisOuTmit.edu> Date: Thu, 30 Mar 2006 10:31:46 -0800 Subject: Re: [EE]: looking for retriggerable 555 monostable circuit The problem is that I'm trying to fix a circuit that's already been committed to PCB with the least ugly kludge possible. It's like the Apollo 13 problem: trying to turn what you have into what you need. What I have is a 555 one-shot and an extra NPN transistor. What I need is a retriggerable one-shot whose output goes high and stays high when the input receives negative-going pulses, then goes low again once the pulses have been gone for a second or two. I'm looking at the inner workings of the 555 to try to come up with a clever way to do this, but I'm running out of cleverness. I don't have access printed resources at the moment, and my Googling has yet to expose a solution. I'd be very grateful if anyone who has come across a circuit that fits this description could pass it along. RR > I'd do it with a PIC10F20X. It would be 1/10 size, cost 1/5 as much, and > would be more reliable than a 555. Take about 5 minutes to write this > code. > > --Bob

Where do the extra "series cap and R and diode" go in this example? Thx, RR Robert Rolf wrote: {Quote hidden}> If he want's to do it with 555, couple the short negative going pulse > into the timing cap using a diode so that the charge is pulled off > for every negative pulse and so the cap never reaches 2/3 Vcc to flop > the flip flop and activate 555 reset. > Use the negative pulse to trigger the 555 as well (sets the flip, > clearing reset and driving output high). > > If the input signal can't handle the cap loading, they he'll have > to use the NPN to discharge the timing cap, and add another series > cap and R & Diode to ground to differentiate the incoming pulse and > turn the NPN on for long enough to reset the cap. > > Robert

piclist-bounces@mit.edu wrote: > The problem is that I'm trying to fix a circuit that's > already been committed to PCB with the least ugly kludge > possible. That makes it more interesting. Do you have the bare PCB, or is the board already assembled? I don't suppose the 555 is a DIP package? If it is, then one possibility would be building a "daughter board" that plugs into where the 555 goes. A wild thought: If there exists a small 8-pin micro (PIC or otherwise) with Vdd and Vss on the same pins as the 555, you could swap that in. Assuming its a 5V circuit.

I have to state that retriggerable monostables are my favourite ICs! These may not be best for him since he has restraints, but they can handle signals of both polarities, and have complementary outputs, and so are very useful. The limited power supply range is a little limiting, though. David Robert Rolf wrote: {Quote hidden}>Or if the OP wants a no brainer hardware solution, 74HC221 retriggerable monostable. > >If he want's to do it with 555, couple the short negative going pulse >into the timing cap using a diode so that the charge is pulled off >for every negative pulse and so the cap never reaches 2/3 Vcc to flop >the flip flop and activate 555 reset. >Use the negative pulse to trigger the 555 as well (sets the flip, >clearing reset and driving output high). > >If the input signal can't handle the cap loading, they he'll have >to use the NPN to discharge the timing cap, and add another series >cap and R & Diode to ground to differentiate the incoming pulse and >turn the NPN on for long enough to reset the cap. > >Robert > >Bob Axtell wrote: > > > >>I'd do it with a PIC10F20X. It would be 1/10 size, cost 1/5 as much, and >>would be more reliable than a 555. Take about 5 minutes to write this code. >> >>--Bob >> >>David VanHorn wrote: >> >> >> >> >>>You're looking for a retriggerable one shot, AKA "Missing pulse detector" >>>I've seen 555 ckts to do this, check an older National semi data book >>> >>> >>> >>>On 3/30/06, Rob Robson <robspam_OUTsilk.net> wrote: >>> >>> >>> >>> >>> >>>>I'm looking for a 555-based monostable (one-shot) circuit whose output >>>>will >>>>STAY high as long as short negative-going pulses are present at the input. >>>>The textbook 555 monostable circuit doesn't do this. I have a spare NPN >>>>on >>>>the board to utilize if necessary. Has anyone come across a 555 circuit >>>>that will do this? >>>> >>>>Many thanks, >>>>RR >>>> >>>> >>>>--

At 12:44 PM 3/30/2006, Rob Robson wrote: >Looks ideal! The absence of base resistor is a little surprising, but I'll >try it. Thanks! Don't be surprised at the lack of base resistor - its not needed. The PNP is configured as an emitter follower. That said: there is a potential problem with the circuit. If the input remains LOW, the timer will never time out. It will time out only if the input remains HI for longer than the RC time constant. If you need a true missing pulse detector, you'll need to differentiate the pulse fed to the base of the PNP transistor. That's the extra RC network Rob Rolf mentioned. Adding that network will allow the monostable to time out and signal the loss of input pulses regardless of whether the input is stuck HI or LO. If you need to detect only the condition of the input stuck HI (the condition of input stuck low is a "don't care"), the single added PNP transistor is all that is needed. dwayne -- Dwayne Reid <@spam@dwaynerKILLspamplanet.eon.net> Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax Celebrating 22 years of Engineering Innovation (1984 - 2006) .-. .-. .-. .-. .-. .-. .-. .-. .-. .- `-' `-' `-' `-' `-' `-' `-' `-' `-' 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.

Hi Rob, Have a look at the CMOS 4538 we use it every where to detect loss of signal very straightforward to use you set C and R to give you a pulse width slightly longer than the ones you are detecting so they will keep on retriggering the monostable so the output will be up while they are there. To deal with the negative pulses I would use a transistor (PNP probably) or for less hassle an inverting op-amp with gain set at 1 or you can even decide to condition the pulses with it. This is the link for the datasheet: http://www1.jaycar.com.au/images_uploaded/CD4538BC.PDF But like some people said use a micro like that you can play with the pulse width that you are detecting and the output of the circuit as much as you can. I had a project where I needed a 250uS every 250mS, I first used a 556 to generate the times and it was an absolute pain to get the times right and then when I decide to change them even worse. So I decided to use a micro to do it ( 68hc08) and I just built the circuit and it took half hour to write the code, changing timing now is just easy and I do not need to get the soldering iron out. Hope it helps. Best regards Luis {Original Message removed}

On Thu, 30 Mar 2006 KILLspampeisermaKILLspamridgid.com wrote: {Quote hidden}> RemoveMEpiclist-bouncesTakeThisOuTmit.edu wrote: >> The problem is that I'm trying to fix a circuit that's >> already been committed to PCB with the least ugly kludge >> possible. > > That makes it more interesting. Do you have the bare PCB, or is the > board already assembled? I don't suppose the 555 is a DIP package? If it > is, then one possibility would be building a "daughter board" that plugs > into where the 555 goes. > > A wild thought: If there exists a small 8-pin micro (PIC or otherwise) > with Vdd and Vss on the same pins as the 555, you could swap that in. > Assuming its a 5V circuit. 12C508 Peter

Yes pins 1 & 8 are power for both a 555 and a 12C508 (at least the DIP package). However, I think the power pins are flipped... 555 has +5 on pin 8 (referenced to pin 1) 12C508 has +5 on on pin 1 (referenced to pin 8) I suppose you could put a 12C508 on the BOTTOM of the board. This would align the power pins properly (assuming a DIP package). May or may not be true for other packages. -- Mark > {Original Message removed}

Getting back to the original question, it occurs to me that if you can deal with an inverted output sense (that is, the output stays LOW until there is a missing pulse), you can probably use the "traditional" time-delay-from switch circuit (figure 8 from http://www.uoguelph.ca/~antoon/gadgets/555/555.html ) This applies the trigger signal to the reset pin as well as the trigger pin. Some change in component values may be needed; IIRC, this will charge the cap from 0 to 2/3 V instead of sticking between 1/3 and 2/3 V... >> A wild thought: If there exists a small 8-pin micro (PIC or >> otherwise) with Vdd and Vss on the same pins as the 555, you >> could swap that in. Assuming its a 5V circuit. >> For "traditional" 555 applications, you can fit a pic10f on a little daughter card that would plug into a 555 socket, with power and "digital" IO (trigger, output, reset) run to appropriate pins and others left disconnected. Indeed, I have several times played with the idea of developing nice GUI (or otherwise human-oriented) PC software where you plug in 555-like design parameters and get out PIC code (or a programmed PIC, for that matter.) However, you quickly run into the realization that there are MANY places where even the cheapest microprocessors is NOT a good replacement for a 555; the micro has very limited drive capability and power supply limits. for instance, and applications that are not quite "standard" are distressingly common... BillW

On 3/30/06, Bob Axtell <spamBeGoneengineerspamBeGonecotse.net> wrote: > I'd do it with a PIC10F20X. It would be 1/10 size, cost 1/5 as much, and > would be more reliable than a 555. Take about 5 minutes to write this code. Bob, Anyway or anyhow you're looking , 555 is cheapest than any microcontroller. Usually 10x555 = 1cheap microcontroller, as price. Output curent capability of a 555 is greatest than any IO. Not talking you have to write the code, or if you want ONE monostable this is waste of time. However there is one problem with 555 monostable: the first false trigger at power up. greetings, Vasile {Quote hidden}> > --Bob > > David VanHorn wrote: > > >You're looking for a retriggerable one shot, AKA "Missing pulse detector" > >I've seen 555 ckts to do this, check an older National semi data book > > > > > > > >On 3/30/06, Rob Robson <TakeThisOuTrobEraseMEspam_OUTsilk.net> wrote: > > > > > >>I'm looking for a 555-based monostable (one-shot) circuit whose output > >>will > >>STAY high as long as short negative-going pulses are present at the input. > >>The textbook 555 monostable circuit doesn't do this. I have a spare NPN > >>on > >>the board to utilize if necessary. Has anyone come across a 555 circuit > >>that will do this? > >> > >>Many thanks, > >>RR > >> > >> > >>--

Vasile Surducan wrote: >On 3/30/06, Bob Axtell <RemoveMEengineerTakeThisOuTcotse.net> wrote: > > >>I'd do it with a PIC10F20X. It would be 1/10 size, cost 1/5 as much, and >>would be more reliable than a 555. Take about 5 minutes to write this code. >> >> > >Bob, >Anyway or anyhow you're looking , 555 is cheapest than any microcontroller. >Usually 10x555 = 1cheap microcontroller, as price. >Output curent capability of a 555 is greatest than any IO. >Not talking you have to write the code, or if you want ONE monostable >this is waste of time. >However there is one problem with 555 monostable: the first false >trigger at power up. > > > I don't agree. The 555 itself costs about 0.25 USD, but the capacitors and resistors and extra transistor to create a reliable retriggerable circuit easily pushes it over $1.50 USD. I can buy the PIC10F200 for $0.50 USD in 100 qty. He didn't say he wanted ONE. He said he wanted to correct a problem on a already-laid-out production PCB. PLUS, It has no power-up glitches. and will run with an accuracy of 3% WORST-CASE, 1% typical. The code is about 20 code words. I will write it myself if he wants. --Bob -- Note: To protect our network, attachments must be sent to attachEraseME.....engineer.cotse.net . 1-520-850-1673 USA/Canada http://beam.to/azengineer

On Fri, 31 Mar 2006, Mark Scoville wrote: > Yes pins 1 & 8 are power for both a 555 and a 12C508 (at least the DIP > package). However, I think the power pins are flipped... > > 555 has +5 on pin 8 (referenced to pin 1) > 12C508 has +5 on on pin 1 (referenced to pin 8) > > I suppose you could put a 12C508 on the BOTTOM of the board. This would > align the power pins properly (assuming a DIP package). May or may not be > true for other packages. The pins can be turned 'inside out' but bottom mounting is valid ;-) Peter

>-----Original Message----- >From: EraseMEpiclist-bouncesmit.edu [RemoveMEpiclist-bouncesEraseMEEraseMEmit.edu] >Sent: 02 April 2006 17:20 >To: Microcontroller discussion list - Public. >Subject: Re: [EE]: looking for retriggerable 555 monostable circuit > > >> >> >I don't agree. The 555 itself costs about 0.25 USD, but the capacitors >and resistors >and extra transistor to create a reliable retriggerable circuit easily >pushes it over $1.50 >USD. I can buy the PIC10F200 for $0.50 USD in 100 qty. You must use very expensive components! Generic small signal bipolars are what, a few cents each? Resistors < 1 cent in any reasonable quantity, leaving only the timing and decoupling caps. Should be doable for well under $0.50 total IMO. Of course, the price does rise considerably if timing demands mean that precision R's and C's need to be used. Regards 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. =======================================================================

On 4/2/06, Bob Axtell <RemoveMEengineerspam_OUTKILLspamcotse.net> wrote: {Quote hidden}> Vasile Surducan wrote: > > >On 3/30/06, Bob Axtell <RemoveMEengineerTakeThisOuTspamcotse.net> wrote: > > > > > >>I'd do it with a PIC10F20X. It would be 1/10 size, cost 1/5 as much, and > >>would be more reliable than a 555. Take about 5 minutes to write this code. > >> > >> > > > >Bob, > >Anyway or anyhow you're looking , 555 is cheapest than any microcontroller. > >Usually 10x555 = 1cheap microcontroller, as price. > >Output curent capability of a 555 is greatest than any IO. > >Not talking you have to write the code, or if you want ONE monostable > >this is waste of time. > >However there is one problem with 555 monostable: the first false > >trigger at power up. > > > > > > > I don't agree. The 555 itself costs about 0.25 USD, but the capacitors > and resistors > and extra transistor to create a reliable retriggerable circuit easily > pushes it over $1.50 NE555 is here 0.1EUR/1pcs. There is no need for any external transistor and RC components are really free. But I can't kidnap your pleasure of using a PIC in everything (even is worthing or not), so let say you have right. :) Vasile {Quote hidden}> USD. I can buy the PIC10F200 for $0.50 USD in 100 qty. > > He didn't say he wanted ONE. He said he wanted to correct a problem on a > already-laid-out > production PCB. PLUS, It has no power-up glitches. and will run with an > accuracy of 3% > WORST-CASE, 1% typical. > > The code is about 20 code words. I will write it myself if he wants. > > --Bob > > -- > Note: To protect our network, > attachments must be sent to > EraseMEattachspamspamBeGoneengineer.cotse.net . > 1-520-850-1673 USA/Canada > http://beam.to/azengineer > > -

On 4/4/06, William Chops Westfield <RemoveMEwestfwKILLspammac.com> wrote: > > On Apr 3, 2006, at 4:46 PM, Vasile Surducan wrote: > > > NE555 is here 0.1EUR/1pcs. > > I wish I had your distributers, then. Here, we have radio > shack at $1.69 (CMOS version only), Digikey at about $0.40, > and Jameco at $0.29. Even digikey's 10k piece price is a > bit more than $0.11... Digikey is a killing source. I'm buying from http://www.comet.srl.ro/main/index.html try a NE555 search. If would be more expensive no one will buy nothing here. Beying a poor country has some advantages. Also being out from EU as long as possible (god help us...) greetings Vasile

At 11:27 AM 4/4/2006 +0300, you wrote: >Digikey is a killing source. >I'm buying from http://www.comet.srl.ro/main/index.html >try a NE555 search. >If would be more expensive no one will buy nothing here. >Beying a poor country has some advantages. >Also being out from EU as long as possible (god help us...) Here's the worst place I found in a quick web search: http://www.micronica.com.au/~micronica/pricelist/chips.htm US 8.00 each with a US$40 plus delivery minimum, and shipping $30 or $45US. ;-) You can get 500 fresh Fairchild RoHS-compliant parts from Mouser (including shipping) for about the price of 5 dusty parts from them. >Best regards, Spehro Pefhany --"it's the network..." "The Journey is the reward" speffSTOPspamspam_OUTinterlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com ->> Inexpensive test equipment & parts http://search.ebay.com/_W0QQsassZspeff

Spehro Pefhany <speff <at> interlog.com> writes: <SNIP> > Here's the worst place I found in a quick web search: > > www.micronica.com.au/~micronica/pricelist/chips.htm > > US 8.00 each with a US$40 plus delivery minimum, and shipping $30 or $45US. > > You can get 500 fresh Fairchild RoHS-compliant parts from Mouser > (including shipping) for about the price of 5 dusty parts from them. > > >Best regards, > > Spehro Pefhany --"it's the network..." "The Journey is the reward" > speff <at> interlog.com Info for manufacturers: http://www.trexon.com > Embedded software/hardware/analog Info for designers: http://www.speff.com > ->> Inexpensive test equipment & parts http://search.ebay.com/_W0QQsassZspeff > They probably do not have any stock at all. At this prices, they can get next day FedEx from Mouser and then ship it to a customer and still make profit. Probably not many customers though. But as the saying goes: there is a sucker born every minute... Sergey

On Mon, 3 Apr 2006, William Chops Westfield wrote: > On Apr 3, 2006, at 4:46 PM, Vasile Surducan wrote: > >> NE555 is here 0.1EUR/1pcs. > > I wish I had your distributers, then. Here, we have radio > shack at $1.69 (CMOS version only), Digikey at about $0.40, > and Jameco at $0.29. Even digikey's 10k piece price is a > bit more than $0.11... The 555 is 1/10 of what you pay for it but their incomes are 1/20 of your income. So the 555 is twice as expensive to them than it is to you ... Peter

On 4/5/06, Peter <spamBeGoneplpSTOPspamEraseMEactcom.co.il> wrote: > > On Mon, 3 Apr 2006, William Chops Westfield wrote: > > > On Apr 3, 2006, at 4:46 PM, Vasile Surducan wrote: > > > >> NE555 is here 0.1EUR/1pcs. > > > > I wish I had your distributers, then. Here, we have radio > > shack at $1.69 (CMOS version only), Digikey at about $0.40, > > and Jameco at $0.29. Even digikey's 10k piece price is a > > bit more than $0.11... > > The 555 is 1/10 of what you pay for it but their incomes are 1/20 of > your income. So the 555 is twice as expensive to them than it is to > you ... Peter, he can't understand that. He must become romanian for a while so the above phrase have some sense. :) greetings, Vasile