zener diode help

forgotmyname

The bike will already have a rectifier though, why is there a need to add something that already exists?

Unless it has 2 outputs with only one rectified, simply add a rectifier to the 2nd and get more power to the DC circuit and a higher charge for the battery.

coffeehound

^ Is the output of the existing rectifier held up at 12V when the engine is off? If not, then yes why not take that to energise the relay.

that

coffeehound wrote: »

Is there a particular reason why no one’s suggesting full-wave rectification as the first stage?

Cheapness. Extra work, less efficient, it only needs to power a relay which is about 40 - 150 ma. you do not need dc for a relay. The op wants something easy, and small. If he uses a triac or scr, then he does not deed a rectifier (needs a diode to protect the gate) and a triac will do both cycles, but both either need ac or pulsed dc, and are fairly efficient

We have been told that 35v is the max, but we do not know the min running, idling, coasting voltage. the worry is that he will do something like pull his clutch in behind a lorry and lose his light, or stop at a junction at night and no one will see him.

forgotmyname

Thats why they have batteries to power the lights whilst the battery is not charging or the charge current is low for some reason.

With modern tech you can probably buy an uprated generator/dynamo/alternator is a far more efficient form.

Plenty of alternators running inside dynamo outer cases. Looks the part but performs way beyond the original item.

Still puzzled why there is a need for all this messing? Whats hard about starting the engine and switching the lights on? Then turn them off and then cut the engine. People have not had issues doing that for decades.

My car has auto lights but i dont use it, i know when i want the lights on or not.

that

"You can't always get what you want, but if you try sometimes well you might find you get what you need"


How about this one, if you leave your lights on and turn the ignition off, you will hear a buzzer?
The lights will power the buzzer, but with the key switched off there should be enough drain to effectively earth a lowish current buzzer. Connect up a small light bulb and try it before buying a buzzer

2-3 diodes and one buzzer?

twhitehousescat

forgotmyname wrote: »

Thats why they have batteries to power the lights whilst the battery is not charging or the charge current is low for some reason.

With modern tech you can probably buy an uprated generator/dynamo/alternator is a far more efficient form.

Plenty of alternators running inside dynamo outer cases. Looks the part but performs way beyond the original item.

Still puzzled why there is a need for all this messing? Whats hard about starting the engine and switching the lights on? Then turn them off and then cut the engine. People have not had issues doing that for decades.

My car has auto lights but i dont use it, i know when i want the lights on or not.

this is not a 1940s brit bike with a dynamo

NO there are no larger altenators available

the charging is good , the battery capacity is low , to low to feed a 3a bulb and a starter motor

forgotmyname

Fit a decent battery then, seems the obvious solution. I have a small SLA battery here than can output 3a easily with little voltage drop. Certainly enough to run a 3a load for several hours.

Heedtheadvice

Oh dear I am still monitoring this thread out of interest.


More lateral thinking this time by that.


A fairly good solutionfor a very simple warning system. Just the two diodes would be required (and a buzzer) to give warning if the bike switched off whilst headlights still on.
Maybe a few shortcomings:
Needs a load of something in the switched side of the ignition circuit that would be low enough resistance relative to the buzzer to cause it to activate (as implied in that's text). If there is not one already on the bike one could be added;


Does not function on a stall (unless ignition switched off) - OP seems convinced it needs to function depending upon alternator output;


If the warning is ignored (likely/unlikely?) it could result in a flat battery. Fitting a timer in circuit would counteract that (then too complicated???); Edit following comment by that: As has been pointed out the drain on the battery by the buzzer is probably negligible compared with the current that will be drawn by the headlight if left switched on despite the warning buzz.......but then I thought if the OP ignores a big light shining, would a buzzer be ignored/not heard too!!!


Does not meet the OP's specification unless the OP is flexible enough to see it is another sensible and logical solution to solve the need (avoid a flat battery or at least reduce the risk) rather than make a circuit to fit the perceived solution.

The technical ones are not insurmountable fairly simply, it is the acceptance of the concept(s) that could be the issue!


.....come on twhitehousescat, use the help you are being given. That is at least two or three reasonable solutions that just need a bit more work......just pick one! ????

that

Heedtheadvice wrote: »

Oh dear I am still monitoring this thread out of interest.

Maybe a few shortcomings:
Needs a load of something in the switched side of the ignition circuit that would be low enough resistance relative to the buzzer to cause it to activate (as implied in that's text);
If the warning is ignored (likely/unlikely?) it could result in a flat battery. Fitting a timer in circuit would counteract that (then too complicated???)
Does not meet the OP's specification unless the OP is flexible enough to see it is another sensible and logical solution to solve the need (avoid a flat battery or at least reduce the risk) rather than make a circuit to fit the perceived solution.

I suspect the green on light, coil, relay and regulator will fairly easily drain a good few milliamps, effectively acting as an earth, especially a bike of this age of technology. Substitute an ammeter for the fuse and turn the key, see how much the circuit drains when it is on but not running, and you soon will find out if the drain is enough or not.

Best of all it is safe, so when the engine cuts off, or low revs there still is light.

Think a loud peizo buzzer on a battery will be negligible, as the light will be on drawing the current

Heedtheadvice

Good latter point, that.
I'll edit my post!