I hated my generators… kept blowing out those damned £4 halogen bulbs when I was trying to commute around the runway at RAF Upper Heyford. It didn’t take long for me to resort to a battery powered light which wasn’t too satisfying either.
Indeed. Generators are more or less a constant current source (not constant voltage, which you may painfully have experienced blowing lightbulbs). LED:s need a constant current source to run at optimal power level. Perfect match. Only add a rectifier (or use a pre-built LED light like the Philips lamp or some B&M lamps)
I replaced my halogen headlamp with an LED – found one that included all the power management electronics AND came in the same package as a standard halogen torch bulb.
I also built a power backup circuit for it, so it stays lit once I stop riding – the MONSTER capacitor I use gives about two minutes of stand-by lighting.
Or use 2 LEDs in anti-parallel configuration. One with light during on cycle and the other will light during the other cycle and together they protect each other against excessive reverse voltage (LEDs don’t like high reverse bias).
It is true that LED lights are the way to go, but if you want to keep your halogen front light you may use the Shimano overvoltage protecting device SM-DH10. It is supposed to be mounted on the backside of a rearlight on a rack, but it is easy to remove it from its aluminium cover and mount it in a different place – just make sure that you have a plain metallic surface as a heat sink. This is what I do when I refurbish spacious ‘historical’ headlamps with (complete) halogen headlamps instead of the original reflector and diffuser.
Zener diodes. Which are built into almost every light I’ve used in the past 10 years. Alternatively, modern LED lights, which are current-driven and which don’t burn out.
Most generators are rated at 6 volts; however, the faster the generator turns, the more power it’s producing. If you get going fast enough, you end up frying the filament in the bulb. So there are two options:
1) A bulb that requires more power to light up….although that might be a problem, because at slow speeds the bulb will either not work or be too dim to be of any use, or
2) SLOW DOWN. Don’t ride so fast that you consistently burn out the bulbs.
I suppose, though, if you are enough of an electrical engineer you could figure out a way of rigging a storage unit (like a small laptop batter) into the system so that the headlight drew a steady source of power from the battery, and then hooked up the generator to constantly charge the battery.
I remember riding downhill and suddenly my light got brighter, glanced back and realised rear had blown. Shrugged my shoulders and made the most of the now usefully bright front light for the few seconds before it blew too.
There is of course an easy solution!
Use a full-wave rectifier to ensure DC and put a Zener diode across the output.
I used a Sturmey-Archer ‘Dynohub’ in the 1960s and with that simple setup, I had no problems. In fact, before I installed the Zener, I put the output across a lead-acid battery. That acts in a similar way and provides a stand-light too
I discovered that the l-a battery allowed some spikes through and blew one bulb. After the Zener, no problems. I believe that Schmidt are among the makers who include a Zener in some designs?
e.g. – http://uk.farnell.com/jsp/search/productdetail.jsp?SKU=9756060&MER=baynote-9756060-pr – A voltage regulator (not a Zener) This should limit the voltage to 6.0V. Using a Zener, any surplus voltage gets turned into heat and must be taken away with a heatsink. However – this device only passes the 6.0V portion of what is generated. There should be a capacitor across both the input and the output, for the purists, to avoid any spikes. It is the current passing through that causes it to heat up and the design makes it easy to bolt it to a heatsink with a 3mm bolt. (any plate of metal exposed to passing breeze)
… and per ‘resistance training’: there is a test of a number of high-end hub generators in the current volume of ‘Bicycle Quarterly’, including drag measurements. As a result, the authors says that (across the board of all hub generators tested) it just takes 1 percent away from your effective speed (lights turned on or off, doesn’t seem to matter much) in comparison to riding with batterie lights – thats not a huge amount I think, and well worth saving all the trouble with those batteries, especially on longer commutes.
My commute is short, so I am even happy with those high-drag cheepo hub generators like the Shimano HB-NX 32 or the Sturmey Archer F-DD …
These things are INCREDIBLY simple. Aside from a switch and lenses, my last home-brew light consisted of: (1) a tiny full-wave rectifier from Radio Slack. Two wires go to the generator (AC) and two go to (2) two 3W LEDs. The + wire from the rectifier goes to the + on one LED, the – on that LED goes to the + on the other LED, the – on that LED goes to the – on the rectifier. All done. For reasons pointed out above, you don’t need a Zener or other voltage regulator with LED lights.
I used that light for six or seven years until this summer, when I discovered that even a cheap LED generator headlight from Avenir (check on Amazon) would outclass it.
I’m doing something new (for me) this winter. I’ve added a small inexpensive flashlight to the front of my helmet, and a yellow/amber flasher on the back elastic strap. Cars can see me better. This would be difficult with a generator. BTW, I experimented with “bottle” generators 20 years ago. I tried different halogen bulbs in different voltages and got incredible light as well as melting several enclosures. But nothing compares to my new rechargable 500 lumen (claimed) headlight that can clamp on whicheer bike I devide to ride that day.
Yeah, the sports boys always underestimate the value of just working hard instead of working out. I bet if you stuck yehuda on their bike (and shaved him) he’d give them a run for their money.
I’ve got the same setup… Alfine dynohub and a B&M CYO. Much better quality light than the tactical LED flashlight I’ve used in previous years. I run it most of the time even in daylight to help increase visibility… and for “resistance training” apparently. (Honestly can’t tell the difference with it on or not)
The only time I ever used a generator was when I was a kid. It was one of those that mounted on the fork and pressed up against the sidewall of the front tire so that it turned when the wheel was turning. I hated it because it made pedaling a lot harder and always felt like I was riding uphill.
generator tech has improved and if you’re willing to spend your cash you can get generators you barely notice which produce light you do notice, unlike the old generators. My winter bike has a nifty setup with two little lights on each hub sticking out and a magnet in the spokes that makes the light blink when it passes. It’s not much, but enough for visibility when I’m in traffic at night.
Some generators are better regulated than others. See http://www.myra-simon.com/bike/dynotest.html
If yours blows bulbs, probably the easiest solution is this regulator: http://www.reflectalite.com/regulatorpage.html
If you’re want to play with electronics, you can put two Zener diodes, anti-parallel, in series with your headlamp. Use Zeners rated for about 8 volts, not 6 volts, since Zeners react to peak voltage, and its “rms” voltage that you want to control. (It’s a little complicated, but 8 volts works.)
But yes, a good LED light is the ultimate solution. The B&M IQ Cyo is great! Luxurious light, good optics (something skimped on by most battery lights) and it works with any generator. B&M’s cheaper LED generator lights are pretty good, too, but not nearly as nice as the IQ Cyo. That headlight, with a Shimano hub generator, makes night riding really great.
btw – @Pops – I am from planet Earth, like you. I was trained in Electronics for my work from the 1960s… Sorry, but the system seemed simple to me.
Twin wires from the generator put out alternating current, voltage depends on speed but designed to be about 6V at normal riding speeds (commuter!)
Ok so then speed freaks go faster and the voltage goes higher – the bulb eventually burns out. Put a higher wattage bulb in and the load will limit the voltage for a while but if you go fast enough, the filament will fail.
A Zener diode is like normal diode – it passes electricity in one direction only. When the designed Zener voltage is reached, it becomes a sort of short-circuit. So any voltage above the Zener setting gets turned into heat.
The device I listed above will take the input voltage and control it, giving out a steady voltage.
Note that a full wave rectifier will multiply the voltage by 1.4! (There is a version that DIVIDES it by 1.4 instead but needs three wires…)
So I guess that some bulb failures are due to a rectifier being used turning the 6V into 8.4 Volts? 6.2V becomes 8.6V etc.
@ Tencon – I have some transformers for effects boxes and a digital recorder which specify the output voltage as 9v DC – but my meter reads their outputs as 12.5V – exactly the 1.4 factor you mention. The devices run fine despite apparently being run at too high a voltage. Interestingly, if I set the meter to record AC voltage, the transformers seem to be running at 27V. Can’t begin to imagine what’s happening there!
As far as I have been able to determine so far – you get what you pay for!
1. ‘Cheap’ – Transformer (tx) – Rectifier – Capacitor – (fuse?) – SMB plug.
2. Professional unit (Expensive) – The above suppies the regulator I mentioned above which has more capacitors around it before the plug.
3. Custom – VERY expensive – Switched mode PSU (too complex to describe. What I spent a lot of my life maintaining!)
I guess the ones you describe fit in 1 above. No need for more unless you get hum… In bad cases of hum, you may need No 3. Usually hum is caused by inefficient earthing/screening of some item…
As for the AC reading – a power specialist would have a better idea but transformers are weird
Some types of meter are ‘pumped’ by the ac from the tx which gives the effect you describe – try doing the reading with a small light bulb across the wires – can be a low-wattage mains type. It would be interesting to hear the results. (I cannot remember why this happens as that memory has not come back to me yet )
I hated my generators… kept blowing out those damned £4 halogen bulbs when I was trying to commute around the runway at RAF Upper Heyford. It didn’t take long for me to resort to a battery powered light which wasn’t too satisfying either.
Anyone have a solution for those light blowing? I have the same problem.
LEDs (and a dyno hub) light your way pretty well.
Indeed. Generators are more or less a constant current source (not constant voltage, which you may painfully have experienced blowing lightbulbs). LED:s need a constant current source to run at optimal power level. Perfect match. Only add a rectifier (or use a pre-built LED light like the Philips lamp or some B&M lamps)
I replaced my halogen headlamp with an LED – found one that included all the power management electronics AND came in the same package as a standard halogen torch bulb.
I also built a power backup circuit for it, so it stays lit once I stop riding – the MONSTER capacitor I use gives about two minutes of stand-by lighting.
Circuit & build instructions here: http://karlmccracken.sweat365.com/2012/03/06/more-on-the-headlamp-upgrade/
Or use 2 LEDs in anti-parallel configuration. One with light during on cycle and the other will light during the other cycle and together they protect each other against excessive reverse voltage (LEDs don’t like high reverse bias).
Not even bother with a http://en.wikipedia.org/wiki/Rectifier so you can charge a capacitor for a short standby light
?
I agree, LED’s, but I use rechargeable lights now… if I were to have a flat after dark, I’d still be able to light the bike while I patch the flat.
It is true that LED lights are the way to go, but if you want to keep your halogen front light you may use the Shimano overvoltage protecting device SM-DH10. It is supposed to be mounted on the backside of a rearlight on a rack, but it is easy to remove it from its aluminium cover and mount it in a different place – just make sure that you have a plain metallic surface as a heat sink. This is what I do when I refurbish spacious ‘historical’ headlamps with (complete) halogen headlamps instead of the original reflector and diffuser.
Zener diodes. Which are built into almost every light I’ve used in the past 10 years. Alternatively, modern LED lights, which are current-driven and which don’t burn out.
Most generators are rated at 6 volts; however, the faster the generator turns, the more power it’s producing. If you get going fast enough, you end up frying the filament in the bulb. So there are two options:
1) A bulb that requires more power to light up….although that might be a problem, because at slow speeds the bulb will either not work or be too dim to be of any use, or
2) SLOW DOWN. Don’t ride so fast that you consistently burn out the bulbs.
I suppose, though, if you are enough of an electrical engineer you could figure out a way of rigging a storage unit (like a small laptop batter) into the system so that the headlight drew a steady source of power from the battery, and then hooked up the generator to constantly charge the battery.
I remember riding downhill and suddenly my light got brighter, glanced back and realised rear had blown. Shrugged my shoulders and made the most of the now usefully bright front light for the few seconds before it blew too.
There is of course an easy solution!
Use a full-wave rectifier to ensure DC and put a Zener diode across the output.
I used a Sturmey-Archer ‘Dynohub’ in the 1960s and with that simple setup, I had no problems. In fact, before I installed the Zener, I put the output across a lead-acid battery. That acts in a similar way and provides a stand-light too
I discovered that the l-a battery allowed some spikes through and blew one bulb. After the Zener, no problems. I believe that Schmidt are among the makers who include a Zener in some designs?
e.g. – http://uk.farnell.com/jsp/search/productdetail.jsp?SKU=9756060&MER=baynote-9756060-pr – A voltage regulator (not a Zener) This should limit the voltage to 6.0V. Using a Zener, any surplus voltage gets turned into heat and must be taken away with a heatsink. However – this device only passes the 6.0V portion of what is generated. There should be a capacitor across both the input and the output, for the purists, to avoid any spikes. It is the current passing through that causes it to heat up and the design makes it easy to bolt it to a heatsink with a 3mm bolt. (any plate of metal exposed to passing breeze)
I must add that THAT controller is a 5V one. Put an ordinary diode between the earth tag and earth for every 0.6V higher you want out.
K’Tesh Fancy not noticing that NATO halogen torch bulbs fitted most lights at the time! LED & hub generator is the way forward
… and per ‘resistance training’: there is a test of a number of high-end hub generators in the current volume of ‘Bicycle Quarterly’, including drag measurements. As a result, the authors says that (across the board of all hub generators tested) it just takes 1 percent away from your effective speed (lights turned on or off, doesn’t seem to matter much) in comparison to riding with batterie lights – thats not a huge amount I think, and well worth saving all the trouble with those batteries, especially on longer commutes.
My commute is short, so I am even happy with those high-drag cheepo hub generators like the Shimano HB-NX 32 or the Sturmey Archer F-DD …
It’s only high drag if you have the brake on Sidewalker!
As a transportation cyclist not seeking “a workout” ride for “training”, I just didn’t think this one was very funny.
transportation cyclists have no sense of humor anyway.
Full wave, Zener, bridge, capacitor??? Take me to your planet…
@Pops:
These things are INCREDIBLY simple. Aside from a switch and lenses, my last home-brew light consisted of: (1) a tiny full-wave rectifier from Radio Slack. Two wires go to the generator (AC) and two go to (2) two 3W LEDs. The + wire from the rectifier goes to the + on one LED, the – on that LED goes to the + on the other LED, the – on that LED goes to the – on the rectifier. All done. For reasons pointed out above, you don’t need a Zener or other voltage regulator with LED lights.
I used that light for six or seven years until this summer, when I discovered that even a cheap LED generator headlight from Avenir (check on Amazon) would outclass it.
When the sparkey’s get to work, it’s like watching black magic to me.
I’m doing something new (for me) this winter. I’ve added a small inexpensive flashlight to the front of my helmet, and a yellow/amber flasher on the back elastic strap. Cars can see me better. This would be difficult with a generator. BTW, I experimented with “bottle” generators 20 years ago. I tried different halogen bulbs in different voltages and got incredible light as well as melting several enclosures. But nothing compares to my new rechargable 500 lumen (claimed) headlight that can clamp on whicheer bike I devide to ride that day.
Yeah, the sports boys always underestimate the value of just working hard instead of working out. I bet if you stuck yehuda on their bike (and shaved him) he’d give them a run for their money.
Hey, that’s my workout every day! Love me some dynohub + B&M Cyo in the dark days of winter. I get to light up all the people I ride by.
I’ve got the same setup… Alfine dynohub and a B&M CYO. Much better quality light than the tactical LED flashlight I’ve used in previous years. I run it most of the time even in daylight to help increase visibility… and for “resistance training” apparently.
(Honestly can’t tell the difference with it on or not)
I’m really surprised Yehuda doesn’t have playing cards attached to his fork in the spokes.. wackaa wackaa wackaa wackaa wackaa
Like
The only time I ever used a generator was when I was a kid. It was one of those that mounted on the fork and pressed up against the sidewall of the front tire so that it turned when the wheel was turning. I hated it because it made pedaling a lot harder and always felt like I was riding uphill.
generator tech has improved and if you’re willing to spend your cash you can get generators you barely notice which produce light you do notice, unlike the old generators. My winter bike has a nifty setup with two little lights on each hub sticking out and a magnet in the spokes that makes the light blink when it passes. It’s not much, but enough for visibility when I’m in traffic at night.
Some generators are better regulated than others. See http://www.myra-simon.com/bike/dynotest.html
If yours blows bulbs, probably the easiest solution is this regulator: http://www.reflectalite.com/regulatorpage.html
If you’re want to play with electronics, you can put two Zener diodes, anti-parallel, in series with your headlamp. Use Zeners rated for about 8 volts, not 6 volts, since Zeners react to peak voltage, and its “rms” voltage that you want to control. (It’s a little complicated, but 8 volts works.)
But yes, a good LED light is the ultimate solution. The B&M IQ Cyo is great! Luxurious light, good optics (something skimped on by most battery lights) and it works with any generator. B&M’s cheaper LED generator lights are pretty good, too, but not nearly as nice as the IQ Cyo. That headlight, with a Shimano hub generator, makes night riding really great.
Why does EVERYTHING have to be a “sport” or competition of some kind?
Well said Zorba – Like
btw – @Pops – I am from planet Earth, like you. I was trained in Electronics for my work from the 1960s… Sorry, but the system seemed simple to me.
Twin wires from the generator put out alternating current, voltage depends on speed but designed to be about 6V at normal riding speeds (commuter!)
Ok so then speed freaks go faster and the voltage goes higher – the bulb eventually burns out. Put a higher wattage bulb in and the load will limit the voltage for a while but if you go fast enough, the filament will fail.
A Zener diode is like normal diode – it passes electricity in one direction only. When the designed Zener voltage is reached, it becomes a sort of short-circuit. So any voltage above the Zener setting gets turned into heat.
The device I listed above will take the input voltage and control it, giving out a steady voltage.
Note that a full wave rectifier will multiply the voltage by 1.4! (There is a version that DIVIDES it by 1.4 instead but needs three wires…)
So I guess that some bulb failures are due to a rectifier being used turning the 6V into 8.4 Volts? 6.2V becomes 8.6V etc.
@ Tencon – I have some transformers for effects boxes and a digital recorder which specify the output voltage as 9v DC – but my meter reads their outputs as 12.5V – exactly the 1.4 factor you mention. The devices run fine despite apparently being run at too high a voltage. Interestingly, if I set the meter to record AC voltage, the transformers seem to be running at 27V. Can’t begin to imagine what’s happening there!
As far as I have been able to determine so far – you get what you pay for!
1. ‘Cheap’ – Transformer (tx) – Rectifier – Capacitor – (fuse?) – SMB plug.
2. Professional unit (Expensive) – The above suppies the regulator I mentioned above which has more capacitors around it before the plug.
3. Custom – VERY expensive – Switched mode PSU (too complex to describe. What I spent a lot of my life maintaining!)
I guess the ones you describe fit in 1 above. No need for more unless you get hum… In bad cases of hum, you may need No 3. Usually hum is caused by inefficient earthing/screening of some item…
As for the AC reading – a power specialist would have a better idea but transformers are weird
)
Some types of meter are ‘pumped’ by the ac from the tx which gives the effect you describe – try doing the reading with a small light bulb across the wires – can be a low-wattage mains type. It would be interesting to hear the results. (I cannot remember why this happens as that memory has not come back to me yet