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13.5 volts into a 555 timer ?

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fatfenders

New Member
I recently purchased a "Canakit" Mini Electronic Timer I want to install on my motorcycle. Instructions indicate I can use 9 or 12 volt input. I would like to just use the MC 12v system but, of course, the voltage can go up to around 13.5
There are few components on the board and I guess the one I would have to worry about is the 555 timer. When they say "12 volts" do the really mean it or could I just go ahead and hook it up to my MC electrical system?
 

Robert_G

New Member
Can you see the actual chip number on the 555 timer? There are different ones, but I believe most can go up to 18V MAX (don't want to run it there all the time). But if this is a device designed for automotive "harshness", you should be fine.

Although not sure I'd hook a 555 timer directly to an auto application without some kind of regulation or filtering at a minimum.
 

Robert_G

New Member
I just looked up that device you have. What is the full chip text and what voltage are the capacitors rated at?
 

Sceadwian

Banned
If 2 extra volts causes a failure in the discrete components on the circuit board the engineer that designed it should be dragged out and shot.
 
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jimlovell777

New Member
If you're concerned and your circuit won't be drawing much current a crude solution would be to add two diodes in series with the power connection.
 

BrownOut

Banned
You can also drop the voltage with a 12V zener, a resistor and a transistor. Connect the resistor and zener to the transistor base, resistor to the B+ and zener to ground, the junction of these two components to the transistor base. Transistor collector to B+ and take the voltage for your project from the transistor's emitter. You'll get about 11.3V from this arrangement.
 

bountyhunter

Well-Known Member
Can you see the actual chip number on the 555 timer? There are different ones, but I believe most can go up to 18V MAX
True, and the IC will eventually die on a motorcycle unless some kind of series R and Zener protection is provided. I found that out the hard way, motorcycle electrics have a lot of transisents on the line. It killed my 555 flasher unit.
 
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bountyhunter

Well-Known Member
If 2 extra volts causes a failure in the discrete components on the circuit board the engineer that designed it should be dragged out and shot.
Transients on auto/MC electrics can easily hit 50+ volts for brief periods but long enough to do damage.
 

BrownOut

Banned
Transients on auto/MC electrics can easily hit 50+ volts for brief periods but long enough to do damage.

Man, that's good advice. I haven't tried to connect anything to my MC yet, but I'll keep that in mind when the time comes.
 

fatfenders

New Member
Thanks much for all the responses...
As you can tell by my question I am just a hack at this stuff but, armed with the information you have provided, I have an idea on how to proceed. Today I drew up a circuit and will try and build it. When I (1) am successful or (2) have to admit to utter defeat I will post results.
 

bountyhunter

Well-Known Member
Thanks much for all the responses...
As you can tell by my question I am just a hack at this stuff but, armed with the information you have provided, I have an idea on how to proceed. Today I drew up a circuit and will try and build it. When I (1) am successful or (2) have to admit to utter defeat I will post results.

If you can define the exact function you need the timer to do, there are probably lots of circuits out there already canned up. I use 555's for the turn signal flasher on my bike right now.
 

Boncuk

New Member
I strongly recommend to use a transil diode to eliminate spikes.

Spikes also kill CMOS-devices before they even start working.

Attached is a datasheet of such a device.

A low drop out voltage regulator would also reduce spikes and ripple.

Use both, the diode and the regulator for safe operation.

Boncuk
 

Attachments

  • 1,5KE-15CA.pdf
    76.3 KB · Views: 91
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MrDEB

Well-Known Member
Transil Diodes ??

looks like it would eliminate spikes in automotive apps.
I was wondering about using two LDO regulators to power a 5V pic circuit in an automotive app.
two regulators in series, one reg for 9v then second for 5v
would eliminate the heat buildup going from 12v to 5v in one step.
sure the total would be 7v across both but heat per regulator would be less.
Just thinking out loud
lets see converting to watts??
 

fatfenders

New Member
Its wooooooorrrking...

First, thanks again for everyone's input. But, in the event, I just decided to run the board directly off the motorcycle accessory wire. I did check it and at idle, it shows 14.5 volts. (Interestingly enough, it goes down to the mid 13's as the rpm is increased.
Here was my rational...
1. (I live near Sacramento CA and try to shop for this kinda stuff at Metro Electronics. But when I went there, they were all out of 12v regulators.
2. So I just purchased a couple at Radio Shack. When installed, and power was switched on/off, about one time in 3 or 4 only about 5 volts would be produced.
3. So I got to think'n... all this stuff is pretty cheap (at Metro ) so what the heck, I will just wire it up directly and if works, fine. If it doesn't, its pretty cheap to remove/replace and try again. In the event, I have been using it for several days now and everything is working just fine. Of course, that could change over time.

So anyway, for any of you who are curious as to just what I am trying to do, here goes.
I know there are all kinds of motorcycle turn signal solutions out there but I just have not liked anything I have seen.
I based the logic of my system on the idea that it is (1) much easier to remember to terminate a process you are currently doing than (2) initiate a process that you are not currently doing.
My basic requirements were:
a. T/S goes on when I manually switch it on.
b.T/S goes off when I manually switch it off, but switching it off requires terminating an action I am currently performing.
c. System is simple and comfortable to use.
So I sorta-kinda designed one of my own, (logic-wise), then purchased the Cana-kit, then posted my question here.
Basically here is what I did. My original T/S switch is a typical slide switch that stays on once pressed. To cancel, one must press a button in the center of the switch. THAT, of course, is the problem. Too many times I forget to punch that button.
So I disassembled the switch and disabled that 'press to reset' button. Now the switch is mom-on.
But it was very awkward to hold the left or right turn signal on while releasing the clutch handle. So I decided I need a simple mom-on push button switch near my left thumb and a time delay on the turn signal switch. The sequence of events being...
(1)tap the left or right turn signal switch which applys that T/S for ,say, a maximum of 3 seconds.
(2)Within the time period, move my thumb down to the 'thumb' switch which keeps the T/S on until I release it
(3) Release the 'thumb' switch when I want to cancel.
I have had it all working for a few days now and am very happy with it.
Its my best guess this could be done more simply than I have, but If you promise not to laugh, you can see my circuit here...
 
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bountyhunter

Well-Known Member
Wow, that sounds complicated. You could just use a 555 timer one shot to power the 555 flasher so that it only flashes for ten seconds (or twelve or whatever you want) so it doesn't matter if you leave the TS switch on since it stops flashing after the timed interval if you do. Next time you go to use it, you notice it's in the on (left or right) position and center it then use it as normal. Or the really simple solution I use: a 12V buzzer that beeps as the TS flashes to remind you to turn it off.;)
 

bountyhunter

Well-Known Member
I did check it and at idle, it shows 14.5 volts. (Interestingly enough, it goes down to the mid 13's as the rpm is increased.
.
If those are accurate readings, your voltage reg/rect are not working correctly.

First, thanks again for everyone's input. But, in the event, I just decided to run the board directly off the motorcycle accessory wire.
OK, it will live for a while.
 
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