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Forum Index : Microcontroller and PC projects : Flash 3 common catode LED lamps.
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| Solar Mike Guru  Joined: 08/02/2015 Location: New ZealandPosts: 1162 |
Plenty on AliExpress , cheap enough; quality unknown!! Mike |
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Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 7832 |
They'll be 555s with a bit sawn off and relabeled. ;) Mouser will do small quantities, but they only have 134 and lead ime is 47 weeks. Digikey are out of stock for cut tape, with a 37 week lead time. Their postage charges are huge anyway unless you are spending quite a bit. RS start at quantities of 2000. I think Farnell will do 200. Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| lizby Guru Joined: 17/05/2016 Location: United StatesPosts: 3348 |
Thanks to all for the very informative thread. I saw circuits of and learned something about high-side switches with Darlington transistors, P-CH mosfets, and N-CH mosfets with "magic black box" photovoltaic drivers. And I ordered some parts. PicoMite, Armmite F4, SensorKits, MMBasic Hardware, Games, etc. on fruitoftheshed |
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| bob.steel Senior Member  Joined: 27/02/2020 Location: AustraliaPosts: 188 |
People say this but I buy only ali-express parts , hundreds to be honest and have never found this sort of practice. Worst I've had was 18650 liIon batteries stated to be 9600mAh (which should have warned me anyhow) and they turned out to be only 25 grams in weight instead of 40 odd they should be and the cells inside were only half filled with plates. Edited 2021-08-02 18:08 by bob.steel |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 7832 |
I get a fair number of components from ebay advertisers and not had any problems. The main thing to remember is that these cheap components may not meet the full specifications set by the original manufacturer. They may, for example, run much hotter than anticipated. It's not usually a good way to buy components if you are producing equipment that is likely to be stressed, where there may be safety issues (class X and Y capacitors for example) or where you need long term reliability. There's a reason that distributors like Farnell and RS are more expensive - they have traceability back to the manufacturer in many cases. Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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CaptainBoing Guru Joined: 07/09/2016 Location: United KingdomPosts: 2170 |
very good advice. ebay etc is fine for small runs etc but for production I would go straight to the source if I can or through an approved disty if not. Manufacturers often sell sub-standard components on to recover some of the costs of the fab, problem is unscrupulous suppliers will buy these up and sell them as cat A parts. A while back, I bought a load of 8MHz AEL XTALS all at 50ppm or better... turned out they were *all* out of spec and some were almost 300ppm out. In that instance, I used by own Freq Meter where I can set an expected value and tolerance and test each one, certificated the lot and sent them back to the supplier who refunded without a word. Also, found the same with RTC chips... these 99p modules on ebay often use a DS3231 - a chip famed for it's time keeping... why then do I have a handful of devices that lose 30 sec a week? In this instance its probably chinese knock-offs rather than seconds. Go to the source if you can! |
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| bob.steel Senior Member Joined: 27/02/2020 Location: AustraliaPosts: 188 |
Its usually mice working at night and covering their tracks I have found. Edited 2021-08-03 13:14 by bob.steel |
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| Volhout Guru Joined: 05/03/2018 Location: NetherlandsPosts: 5036 |
These 3231s may be devices that where never factory calibrated. They have all tuning parameters ser 0x00. There is temperature calibration, Vcc calibration, aging, all tuning parameters that are set when you buy a genuine chip. PicomiteVGA PETSCII ROBOTS |
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| CaptainBoing Guru Joined: 07/09/2016 Location: United KingdomPosts: 2170 |
 Those b*stards again!  My missus wakes up feeling ragged after a night's kip and has a theory she is being kidnapped by aliens and forced to work in a mine overnight before being brain wiped and returned to bed. Could be them too |
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| Tinine Guru Joined: 30/03/2016 Location: United KingdomPosts: 1646 |
 The way things are going, she might be seeing the future  |
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| bob.steel Senior Member Joined: 27/02/2020 Location: AustraliaPosts: 188 |
Well with a name choice like that I would venture to add there is another possible culprit right beside her. |
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| CaptainBoing Guru Joined: 07/09/2016 Location: United KingdomPosts: 2170 |
hah! you are the first to ever notice - well done Although it maybe thought a somewhat unsavory piece of London slang, it actually comes from my landing the first few times it's not me - properly medicated I am out like a light. |
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| Tinine Guru Joined: 30/03/2016 Location: United KingdomPosts: 1646 |
Huh? What, me? Tinine is the name of a band that I played in during the early eighties. At the time, I was working with a Texas Instruments product TI-9 and we called it Tinine and so I used it for the band. Does it mean something bad? Google came up with nothing, not even "awesome band with a brilliant guitarist" |
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| CaptainBoing Guru Joined: 07/09/2016 Location: United KingdomPosts: 2170 |
this would be a good thread in the "other" category, like the photos - people with non-obvious nicks... how did they come about and how do you pronounce them (I always see yours as "tinny" - i.e. can of beer styleee) Edited 2021-08-05 15:35 by CaptainBoing |
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| Mixtel90 Guru Joined: 05/10/2019 Location: United KingdomPosts: 7832 |
MIXTEL was a part-time viewdata bulletin board that I ran many moons ago. A Speccy, Interface One and 3 microdrives with a modified (to make it auto-answer 75/1200) VTX5000 modem. MIXTEL stood for "Mick's Telephone". :) I rather like it and I've kept it as a "handle" in a few places on the 'net. Mick Zilog Inside! nascom.info for Nascom & Gemini Preliminary MMBasic docs & my PCB designs |
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| bob.steel Senior Member Joined: 27/02/2020 Location: AustraliaPosts: 188 |
OK Can I get some advice please . Going back a bit I settled on a circuit and its result inverts the signal so its off when it should be on . etc So whats can i add to invert it again so I don't have to convolute the running program . Here is the circuit again. This is nuts and volts circuit and i have 28 volts on the top and I'll have 3 drive pins to 3 of these circuits on each of 20 boards so just the minimum of components .  Edited 2021-08-05 18:19 by bob.steel |
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| CaptainBoing Guru Joined: 07/09/2016 Location: United KingdomPosts: 2170 |
personally I don't see any problem with having "active LO" signals (which is what you have above). It can be inverted in the software easiest or if you want a hardware solution, just put another transistor on the base of Q as shown below (your existing Q is in the red box) to act as a simple inverter. Any small signal NPN will do for the two transistors - if you have old stock of BC107 or similar, use them here and give the old boys purpose. 1K will limit drive current to 5mA which should give a good solid turn-on other ideas do exist...  Now when your signal goes high, new-Q turns on and connects the base of Q to GND - turning it off. When your drive goes low, new-Q turns off allowing the base of Q to drift rapidly up to 5V turning it on with some gusto. Edited 2021-08-05 18:51 by CaptainBoing |
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| PeterB Guru Joined: 05/02/2015 Location: AustraliaPosts: 655 |
G'Day All I hope that DRIVE IN is via something like 10k. Then remove that signal from the Arduino pin and connect to +5V. Then connect the emitter of Q to the Arduino pin. (after disconnecting GND.) It might be a good idea to increase R2 a bit to reduce current in Arduino pin. You now have a common base circuit. Peter CB does EBay sell gusto?  P Edited 2021-08-05 20:14 by PeterB |
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| CaptainBoing Guru Joined: 07/09/2016 Location: United KingdomPosts: 2170 |
ooh! I like that! poor imitations I'm afraid... as with Havana cigars - best rolled on a maidens thigh (mi gusto... no? I'll get my coat Edited 2021-08-05 20:21 by CaptainBoing |
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| PeterB Guru Joined: 05/02/2015 Location: AustraliaPosts: 655 |
Do you agree that my humble idea would work? I'm afraid that I am losing confidence in my hardware skills. I'm still working on mi gusto...no? etc. Sadly I live in a place that was built for Poms after WW2 (and a few Aussies). We were knee deep in them for years but we eventually chased most of them out. I also worked with many Poms but after all that I still have trouble with their humour. Peter Didn't see the oh I like that Edited 2021-08-05 20:31 by PeterB |
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