Picaxe right for my project?

Shafto

Senior Member
I'm creating some custom LED tail lights for my car, and I'd like the turn signals to be sequential. I'll probably use 7 or 8 segments of LEDs which I would like to fill at an adjustable rate, and then turn out at a separate adjustable rate.

I was planning on using a couple different 555s feeding into 2 different decade counters to get the job done, but SCRs are a pain to turn off remotely and NPN/PNP transistor arrays than can handle the amperage of each segment will add a lot of cost to my project, so I figure using Picaxe controllers may be my answer, then I can just use the outputs to turn on cheap transistors to run each segment ... unfortunately I've never worked with a mirco controller and I have no idea how I would make the ramp up (array fills sequentially) and ramp down (array turns off sequentially) adjustable with the inputs. Again use a couple outside 555 timers, make the picaxe listen to one of them as it fills the array and then stop, and listen to the other one as the array turns off? or can the picaxe do all of this internally?

I've read, and am reading more about what I can do right now, I've just never worked with code or anything, and I'm not really sure what I can do and what I can't.

Thanks a lot for any help.
 

BeanieBots

Moderator
More to the point, have you ever worked with electronics in a car environment?
Are you aware of the supply spikes 1.5kV. 20mS 20v surges.
Do you know how to protect the micro from these effects?
Is what you are doing legal?

Besides that, the PICAXE should be able to do all that you want. No need for any 555's.
Start simple. Read the interfacing manual and hook up a few LEDs.
Turn them on and off. Then start to build up the sequence you want using pause statements. Once you have a sequence, put it in a loop so that it repeats.

Have a browse (search) around the archived threads to find out about electronics in cars. The software and functions is going to be the least of your problems!
 

Dippy

Moderator
I dunno how old your car is but may I just mention a caveat (warning) on some very new cars.
A mate of mine works in a garage (car workshop) and mentioned that some very new cars are using modulated signals to switch things - reducing the size of the wiring harnesses.
I couldn't believe it but this,apparently, included the handbrake function on one car (Focus C Max maybe?). (I haven't checked as I hate Google so you can Google away to suss it out).
Note: Check the price of modern car towbars/electric pack.


The point I'm trying to make is that in addition to power supply filtering/suppression you should also think of any modulation your device is putting onto the main wiring 'upstream'.
Transient suppression/filtering is pretty easy and, as mentioned by BB, something you MUST build into your design.

Anyway, that's just some thoughts to be chewed over in a few years time when we're thinking of fiddling with the wife's second-hand 10 year old CMax.
 

manuka

Senior Member
Shafto: It's been specified perhaps a zillion times on this forum that hobbiest level PICAXEs should NOT be attached to any active part of a roadworthy car's electrics. This is largely to cover legal issues in case something- like that bug in the last subroutine line etc- goes wrong...
 

hippy

Senior Member
1.5kV supply spikes? How does that happen, and how can you protect against that?
Induction effects from the coil firing the spark plugs and all manner of things which cause change of current while driving, starting up or switching off. Some vehicles are worse than others. There are also brownouts and negative pulses to worry about. Having TV or radio interference when a vehicle drives past is the closest we get to seeing it.

Protecting against it is a bit of an art form and open to much debate. Careful, knowledgeable design and experience in the field seem to be the main ingredient. Get it wrong and you can compromise the entire vehicle's integrity, and that's not wanted at high speeds.

An issue not mentioned is what local legislation says an indicator must do or not do.

Fitting anything to a vehicle can adversely affect your insurance and own liability. If your car bursts into flames the insurers may well say it's because of your addition even if it wasn't. If they want to play nasty ( as if they would, just to save some money ! ) can say you didn't get approval first so your insurance was invalid and you're in a deep legal mess if your car has been involved in an accident. All of a sudden you find you're an uninsured driver and the police may be knocking on your door shortly.

That's not to say don't do it, but that's the recommendation I'd give most people.
 

Dippy

Moderator
I agree with hippy's caveats and anyway, are sequential lights (e.g. turn indicators) legal anywhere?

Go and get an electronics catalogue catalogue and look up things like; 'suppressors' 'transient voltage suppressor', 'chokes', 'inductors' , 'capacitors' 'VDR' 'Varistors' and many other last names.
Then Read UP and absorb. It's not rocket science or magic.
Do the calcs , pick'n'mix, play around (don't tell my missus), use your noggin and Bob's your Uncle , you'll have made a suppressor suitable for the app.

There may be numerous circuits on the Internit, use one of those ghastly search engines.
 

BeanieBots

Moderator
Once you've fitted your bits, in the UK, for £25 you can then get an "Engineer's Certification" which will keep the insurance people happy.
A "modified" car automatically goes to the top insurance group (and becomes uninsurable if you're under 25) but after certification you can get it bumped back down or even negotiate an even lower rate. Well worth the money. It's saved me thousands over the years in reduced premiums on custom cars.
 

Fowkc

Senior Member
Once you've fitted your bits, in the UK, for £25 you can then get an "Engineer's Certification" which will keep the insurance people happy.
I'm curious: Does that certification actually require any knowledge at all, or just having a spare £25? If so, pay day is coming up...
 

BeanieBots

Moderator
I'm afraid it does. In fact it's worse than that, the certification states that the work is done to a "satisfactory standard" and that the vehical "conforms" to legislation. eg if you have added a turbo, you must also have up-rated the brakes & suspension and not just made it go quicker without taking everything else into account. If you have added any electrics, it must conform to wiring standards (including cable colour, gauge & fuses). etc. etc.

What qualifications you actually require to certify I honestly don't know.
Probably similar to those required to give an M.O.T.
 

hippy

Senior Member
I'm curious: Does that certification actually require any knowledge at all, or just having a spare £25? If so, pay day is coming up...
I'm intrigued also, especially given the relatively low fee involved. I'd have expected certification to involve showing circuit diagrams, UL ratings for components used, results of spike supression tests and so, basically proving "this is safe". I bet they just look out the window, check it's not on fire, parked in a wall and no trail of bodies in its wake, then tick a box :)

How do they ensure that what's been certified on the day is that which is on the car when the insurance assessors come to scrape up the pieces and check it hasn't been modded ?
 

Shafto

Senior Member
All of the LEDs I'm using are DOT approved lumileds Superflux LEDs.

Leds make a car safer, their instant on action can save you 20meters stopping distance on the highway compared to incandescent bulbs, not to mention they suck less power, and therefore less fuel. The sequential flashers will still flash at the same rate as the stock bulbs, the effect will be very subtle, it'll look somewhat like an incandescent lighting up quickly and then fading out a little slower.

The LEDs are all fed by sharp low loss voltage regulators, and the marker lights are dimmed by PWM. It won't be a problem to also regulate the voltage to the picaxe chip.

I realize that I can play around with the high and pause commands to acheive the effect I want.. but then the rate wouldn't be adjustable without reprogramming the chip, I'd like to have the speed the array fills and the speed it goes out each separately adjustable by a pot. That's why I was thinking of 2 seperate 555s to have the picaxe listen to one while it fills up, and listen to the other one as it goes out.

I am going to order up some picaxe chips to play with, I'm sure I can figure it out with all the help that seems is available here, I couldn't believe 7 replies on my thread when I woke up this morning, that's great stuff. I just wanted some input as to whether I was looking in the right direction as how to control my sequential arrays.
 

BeanieBots

Moderator
You're probably right Hippy. Bottom line is that it is a piece of paper well worth the money so I don't complain.
Let's face it, most of us know (or know someone who knows) a garage where you can get M.O.Ts by post:eek:

@Shafto, let's forget cars for a moment and get back to controlling LEDs.
Consider the 28X or 28X1.
It has four analog inputs which could read four POTS and two background PWM outputs which could fade up/down two independant LED arrays.
Sounds like what you need.
 
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Shafto

Senior Member
I'll get a couple 28s, but I was thinking I could get away with the 18, one for each side (left blinker/right blinker)

I would use the pots to control the speed of the 555pulses, I shouldn't need to feed the pot signal right into the picaxe I don't think? It should be possible to have the 18 count up 1,2,3,4,5,6,7,8 making each output high as it sees a pulse from the first 555, and then start counting down while reading the second 555, sound like a good way to do it?
 

BeanieBots

Moderator
The whole idea of connecting the POTs to the PICAXE is because the PICAXE will be doing EVERYTHING.
It can do the timing, flashing, and fading. What do you want the 555's for?
 

Shafto

Senior Member
because I don't know how to make the picaxe do the timing.. I'm totally unsure how I would convert the signal from the 2 pots into something the picaxe will see as a timing multiplier of some sort, and I can command it to listen to either one? That's great, like I said I'll get some 28s, if I can figure that out even better.
 

BeanieBots

Moderator
That's what this forum is for;)
Have a read of the commands in the manual.
There's the pause command. waits a defined number of milliseconds.
ReadADC. Gets a value from the POT.
Adjust the pause in acordance with the POT value and you have a variable delay.
Then there's PWMout. Could be used to fade the brightness of LEDs.

With the 28X1 there is also an internal background timer which might be of use.
What you will certainly find, is plenty of help from everyone here.
 

Shafto

Senior Member
Well this has got me excited, and thinking, maybe I can run everything for my project through a 28x chip, the blinkers are the hardest part, all the marker/brake lights do is come at with a PWM during marker operation (headlights on) and then get full power then the brakes are pressed.

I suppose I could control the PWM output from the chip with a pot aswell? so I can adjust my marker lights to the right setting? The sharp voltage regs I'm using have a built in transistor "on-switch" perfect for pulsing with the PWM, then I can just use a blocking diode on the output from the picaxe and run the brake signaling wire with another blocking diode into the switch, so when I hit the brakes the voltage reg just spews power full time.

Do I need 1 chip for each side though? because I want to power 8 seperate arrays for each signal, I saw another post with somebody saying they were controlling 56 seperate LEDs I think? so would it be possible to have the same 8 outputs somehow differentiating between left and right signals? ..I suppose I could use another 2 outputs on transistors, so when left signal is activated the output to the left transistor will go high and power will only go to the left array, even though the transistors for each section of each array will be firing power will only be available for the triggered array... then both for hazard lights.

Wow this is better and better the more I learn about it, does it sound like I can do all this from one 28x chip? ..or I could even get the 40, it's only about a dollar more.
 
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manuka

Senior Member
Shafto- electronic excitement is our business! Strongly suggest you park the car for a spell & first GET TO KNOW just what these PICAXE darlings can do. Even the humble (2004 era) 08M has yet to have it's applications maxed out. Who knows - you may never get round to driving the car again! I see you are on Vancouver Island where the roads are pretty quiet outside Victoria anyway. Be super respectful of Canadian driving legal issues, especially if you are still a minor! I used to live in BC & well recall the provinces red tape paperwork nightmare... Picaxe breadboard layouts preferred by the way. Are you up with these? Stan in NZ
 
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Dippy

Moderator
Shafto, why don't you draw a nice neat schematic and post it.
Remember, YOU know exactly what you're trying to achieve, WE don't.
We can guess - but a picture paints a thousand words...
(Is there an emoticon for Crystal Ball?)

The schematic will also clarify in your mind the number of connections needed.
Once understood, people may be able to suggest hardware alternatives to keep connection numbers down. Believe me, if you have a spag-bol breadboard you'll find it difficult to put it onto pcb - I assume you don't want a Stan Breadboard in the boot/trunk of your car?
 

BrendanP

Senior Member
Just a few observations on car mods and engineering certificates here in Australia.

A while back I cut the roof off a VW bettle and stiffened the floor pan and put a roll bar in. I cracked open the trusty arc welded and did the welding myself and got it certified by a engineer and registered. I have no welding trainning at all, my philosophy is crank up the amps and pour in the heat! I still got it passed first time. Anyway, a amatuer with some skill can get things done. I remember bending the RHS steel in the fork of a tree in the front graden to fit the shape of the floor pan.

Shonky road worthy certificates are common here too. You don't have to get one each year here in Victoria however, only if the cops put a defect notice on the car. My brother had a guy 'on tow' who used to write them out for a $50 car sight unseen. I utilised his services a few times. I love those Arthur Daley style characters.
 

manuka

Senior Member
"Kiwi" board

Dippy -"if you have a spag-bol breadboard you'll find it difficult to put it onto pcb - I assume you don't want a Stan Breadboard in the boot/trunk of your car?"

Breadboards are best for evaluation & refinement & I certainly DON'T recommend them for final use. Bright Spark Andrew here in NZ has recently designed & commissioned (yeah- via China) a particularly nifty fi-glass silk screened "Kiwi Patch Board" that has had superb local adoption. The idea is to just lift over parts from a breadboarded version to these "paint by number" style. In fact we should start promoting them on the forum, as they're dirt cheap & look extremely impressive as a soldered prototype. Andrew has of course allowed for the Rev.Ed programming socket,as well as a 7805 & smoothing cap etc. Anyone want details?
 

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Shafto

Senior Member
Ok, thanks for the help so far guys, sometimes you see something so clearly in your head you don't realize that others can't tell what you're thinking!

So I drew up a schematic as you suggested Dippy, sorry for it's crudeness but I think it gets the point across.



First off I see on the Canadian distributor website for picaxe that the 28x has 9-17 outputs and 0-12 inputs, so I inputs 5,6, and 7 I used as outputs, in my diagram.

Marker Input VR controls the PWM duty cycle for the marker lights.
Signal Ramp up VR controls the speed which the sequential array lights.
Signal Ramp down VR controlls the speed which the sequential array goes out.

Left Turn Signal Input triggers all 8 NPN transistors to conduct sequentially, but it only triggers the single Left Side PNP transistor, so only the left array has ground, and only it will flash. Ditto for the Right Turn Signal Input, and when both are triggered (hazard lights) both arrays will get ground.

By adding that PNP transistor I should only need 8NPNs instead of 16, and only 1 picaxe chip to control both sides.... I think.... I have some experience with electronics, but none with mircos.

I forgot to draw the input to trigger the marker lights, but when they go on the chip will send the PWM signal to keep that at the right brightness using the input pot, then when the brakes are applied the transistor feeding the arrays will just go on full time..

Excuse the LEDs being positioned the wrong way, didn't notice that until the end.

So now that you've all got a better idea of what I want to do, does it look like I'll be able to pull this off?
 
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leftyretro

New Member
"So now that you've all got a better idea of what I want to do, does it look like I'll be able to pull this off?"

Looks very workable to me on the hardware side, don't forget to put add some fuses and possibly heat sink your switching transistors. Best to breadboard the whole system to look for issues before commiting to final construction.

Now for the code :rolleyes:

Is the left and right blink inputs a steady high when commanding a blink or do they pulse like normal blinkers? You may have to think that timing sequence out.

Good luck and look forward to a U-tube video showing off how useful and powerful the Picaxe system is. :)
Lefty
 

Shafto

Senior Member
Thanks for some input Lefty,

The signal pulse will remain high for the length of time the stock incandescent bulb is lit, but I think I'd rather not use it for timing, just use it as a pulse to start a sequence that I will time with the pots to work.. though I have no idea how to work out the code, I'm sure I can learn!

I think the problem with using the signal pulse for timing is that it wouldn't be long enough.. the stock signal blinks on/off about 50/50 I think.. With the sequential array the "off" time will be a lot less, as the sequencing will take longer.. but all along still getting the blinking effect.. ei. By the time the array fades off it'll be pretty much right to start loading up again.

Here's a quick little vid of a sequential LED turn signal, but this one just uses a decade counter and only counts out, like I say I want mine to count out very quickly, and fade off slower.. As you can see it's not on/off 50/50, it's more like 70/30, and still looks quite subtle, mine will be even more subtle.

http://www.youtube.com/watch?v=1S742mOvVXw

edit: when I say fade I don't mean dimming, I mean the separate segments of LEDs in the array turning off sequentially.
 
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Dippy

Moderator
Quote Stan: "Breadboards are best for evaluation & refinement & I certainly DON'T recommend them for final use. "

Stan, mate, I was having a little joke. I love breadboards, use them a helluva lot, but I don't bother with the felt tip pen :)

Shafto: Nice Schematic.
I'm a little confused with the transistor switching on the marker/brake part. What kind of transistor are you thinking of using for switching the 9V supply (high side)? I realise you commented on the LEDs being the wrong way round but your diagram implies simple NPNs which would be unhappy. And PNPs with no base current limiting = bye bye PICAXE.

I think you ought to read-up/experiment with transistor switching first to see what happens. They are not magic solid state relays. And you should have resistors to bases (or gates if going the MOSFET route).

It would also be a very good idea to have decoupling caps (pos. R-C) and transient suppressor right next to PICAXE +V/0V and a healthy capacitor near the high sided transistors (whatever type you use). The first reduces noise and nasty blips getting to PICAXE which could cause malfunction or failure. The second reduces noise from your pwming getting back onto the vehicle supply. You may have to introduce further suppression but you'll only find that out later.

I'm not going to bang on about vehicle safety, you're on a mission here - just be careful and sensible and legal. Crummy boards with weedy grounds and wiring should be avoided.

PS. What is your 'level' in electronics/coding?
 

Shafto

Senior Member
My level in coding is never, and electronics, well novice for sure, but I could easily get the marker/brake function done without the picaxe, well, I could comfortably do everything really, even a one way sequential array like the one I posted the video of, it's just this fading back part that's led me to the picaxe, and now I'm finding that it can take over pretty much everything with this little chip. I'd like to give it a try.. I can always lower my sights if I don't quite make what I'm aiming for here and go back to some components, but I'll deal with that if I have to. I'm very thorough, nothing will be thrown together here. Everything will be working on the bench before it's rigged up, it'll be a quality job for sure.. There will be lots of pics along to way to prove that!

I want to learn about this anyway, I can just imagine all the other projects that will come to mind once I have a grasp on how to use these things.
 

BeanieBots

Moderator
Now I've seen the video it's a lot more obvious what you want to do.
A 28X/28X1 should be more than up to the task and "it will work on the bench".
The fun will really start when you put it in the car, but you've got that joy to come a I keep harping on about it until get to that stage.

Think binary, any number between 0 and 255 can be represented as 8-bits
00000000=0
00000001=1
00000011=3
00000111=7
....
11111111=255

All you need to do is build that sequence which is just:-
start at 0 then add 1 output, times 2 add 1 output, times 2 add 1 output...

That can be put inside a simple loop

main:
b1=0 'all off
For b0 = 1 to 8
b1=b1*2+1 'set next sequence
pins=b1 'present the 'number' on the outputs
pause 250 'wait for 1/4 second
next b0 'repeat until all 8 are on
pause 1000 'leave all on for a second
goto main 'repeat the whole sequence.

Knock up a breadboard and start experimenting with just a single LED on each output to start with. Get the sequence right and then start expanding.
For example, replace the fixed pause value with a variable, then change the value of that variable from a reading you get from the analog input which you have connected a POT to.
To count down, just have a similar loop but divide by 2 each time starting from 255.

Start small and work your way up. Then add in the extra LEDs and 12v power and then .... try to get it to work in car:eek:
 

Shafto

Senior Member
Thanks Beanie, now to get the parts...

Dippy, the marker/brake light will actually be switched by a transistor built into the sharp regulators I'm using, they have a built in on/off switch.

I also plan to reverse the scheme in my diagram, the 2 PNP transistors will be switched to NPN (I'll just use the transistors built into the regulators here too) and then switch the 8NPNs to PNP, so the ground is sequentially switched.. that way I can make use of the built in switch on the regs... but I don't fully understand the need for base limiting current on the PNPs though? they must drain the energy to ground? and over-draw the picaxe chip? some resistors won't be a big deal though, 1k or something? I suppose I'd have to study the transistor datasheet.

anyway.. I will be experimenting a lot here, can't wait until all the parts come in.
 
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BeanieBots

Moderator
Basic transistor theory:- (not FETs)
A transistor is a CURRENT amplifier.
The amount of current that can pass between collector and emitter is the amount of current fed intop the base multiplied by the transistor gain known as hfe.
The base 'looks like' a diode to the driving signal. Hence, if a voltage above about 0.6v is applied, it will sink enough current to melt itself.
The PICAXE cannot supply enough current to do that but will keep trying until IT melts instead.
Hence, the resistor value should be high enough to protect the PICAXE and low enough to allow enough current to drive the transistor hard on. That is, the current that COULD pass through it is higher than the current that needs to pass through it.
 

moxhamj

New Member
1k on the base will work fine but at 5V that is 5ma per pin and that might be a bit much for the picaxe if all were on at once. I tend to use 2.7k.
 

Shafto

Senior Member
Great info, thanks again.

Check out this little goodie I found

http://focus.ti.com/lit/ds/symlink/uln2803a.pdf


"The ULN2803A has a 2.7-kΩ series base resistor for each Darlington pair for operation
directly with TTL or 5-V CMOS devices."

It's the same chip used on the picaxe project board, I think it'll be perfect.. now I just need to figure out what resistors I need to use in line before the transistor in the voltage regs, not really sure how to figure that out.. but I'll start searching, I wonder if 2.7k would be appropriate here aswell.

I'm a little confused by the pinout on the ULN2803A, the inputs are obviously the bases for the transistors, but then the outputs seem to be the collectors with the common pin being a common emiiter? I thought it would have been the other way around.. Oh well, I'll figure it out when I'm playing around with them..

Part number for Sharp regs:

9 volt - PQ09RD21
12 volt - PQ12RD21

I think I'll just ditch any PNP transistors, I'll just use 2 of these ULN2803A since they're so cheap, and then outputs from the picaxe to the transistors on the voltage regs to switch main power onto one or the other side.
 
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Dippy

Moderator
Thanks for those numbers Shafto . I've just had a squiz, they look really useful.
Expensive?

Re: ULN2803 ('Old Faithfull')
I think you're still under the impression that a transistor is an all purpose solid state relay.
Well, it can be, if you understand (even roughly) how they work.
The ULN2803 is a Darlington NPN with some resistors generously included.
An NPN device like this is a Low Sided switch (pedants keep quiet).
It's like having a toggle switch which connects your item (eg LED) to ground 0.
Like this:
+V
|
res
|
LED
|
Switch (or ULN2803) <- 'Low Side'
|
0V (the relatively negative side)

Whereas, PNP can be used as a 'high sided' switch, which is usually where switches go in electrical circuits. But, as usual, it's 'Horses For Courses' and you can't shove PNPs in any old way. For low level switching I uses P-Channel MOSFETs quite a lot too.

I think a basic book on electronics may be VERY helpful for you to get your mind round the simple concepts.

But, I'm sure you'll get this to work pretty soon now. Usng this ic will (should) allow you to produce a neater and safer pcb.

As mentioned before, testbench it thoroughly. And , as also said before, you must have some sort of noise/transient suppression in the supply to your PICAXE.

Go for it :)
 

BrendanP

Senior Member
Dippy, you mentioned using transient suppressors a couple of posts back. Is this only needed on car based projects like this one or is it good pratice to include them on all projects. I use decoupling caps on the power and reset pins as a matter of course now. Should I use transient suppressors too to give increased reliability ?
 

Dippy

Moderator
I wouldn't use them on all projects.
This particular project is for something on the car electrics where various sparklies may be kicking about which would probably upset or damage the processor.

For portable battery projects and most mains adaptor supplies your caps are fine.
For something that is connected long-term to a cheap mains power adaptor (e.g. a wart) then I may think about it for the once in a blue moon transients that you may get up the mains e.g. Lightning or the Anne Summers factory next door doing an open day.
It's all about probabilities and if you have the space in your box and 50p in your pocket then it may be worth including in some mains-powered devices.

In the past I have had problems with projects being affected by mains switching and transient & RC suppressors (I admit they were on the mains side) cured it.
Sometimes you only discover these things after, so if you are suspicious of a power supply then Mr Scope should be brought into action. Or, if you don't have a grand for a Tektronix then buy a couple of suppressors.

I shall now switch into cliche mode and say:-
"Horses for Courses"
&
"Better Safe than Sorry"
 
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Shafto

Senior Member
I'm gonna have to go read up on transistors here.. I thought that NPN switched + side and PNP switched ground, but this NPN darlington driver switches ground? hmm.. that will actually work better for me.

Gotta look into these suppressors as well, I thought the 9 volt reg plus another 5 volt reg with decoupling caps would be good enough, but I'll check that out later.. as I'd like to get it working on the bench as soon as I can. parts are on the way.. This way I'll have a long time to test it, as I still need to do some more work to the tail lights themselves, and source some prismatic reflector material from somewhere, haven't been able to find any pieces large enough.
 
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BrendanP

Senior Member
I didn't know what/who Anne Summers was.... google set me straight....

".....Apparently Apple is non-too-impressed by Anne Summers latest adult gadget: the iGasm....." Thats enough information for me to deduce the nature of Anne Summers business!

Ok, I actually have under development a piece of equipment that will run off mains via plug pack, and usually in remote areas where it will be subject to lightening strikes on the power lines, surges etc. I'll use a suppresser, thank you for the advice.

Are there any pitfalls/traps for the unwary in using supressors that I should be aware of that a data sheet /google search/wiki won't tell me?
 

BeanieBots

Moderator
Are there any pitfalls/traps for the unwary in using supressors that I should be aware of that a data sheet /google search/wiki won't tell me?
That depends on how and where you use them.
When applied across power supplies, there's not much to it except putting them on the correct part of the power line.
When put across switch contacts, you must remember that the switch no longer isolates and small currents can still flow when off.
 
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