|
|
Thread Tools | Display Modes |
#1
|
|||
|
|||
When do blinking lights become just plain annoying?
On Mar 22, 1:40*am, James wrote:
There is some, albeit poor, current regulation by most bicycle alternators, but not voltage regulation as you know. I'm curious about your claim that current regulation by these things is poor. James, why not try some measurements? Both current and voltage, into (say) either a matched halogen bulb or a power resistor. Give us the results. - Frank Krygowski |
Ads |
#2
|
|||
|
|||
When do blinking lights become just plain annoying?
Frank Krygowski wrote:
On Mar 22, 1:40 am, James wrote: There is some, albeit poor, current regulation by most bicycle alternators, but not voltage regulation as you know. I'm curious about your claim that current regulation by these things is poor. Look at the output from a semiconductor voltage regulator. The output may be within 0.1 or 0.01% of the desired output voltage. JS. |
#3
|
|||
|
|||
When do blinking lights become just plain annoying?
Frank Krygowski wrote:
On Mar 22, 1:40 am, James wrote: There is some, albeit poor, current regulation by most bicycle alternators, but not voltage regulation as you know. I'm curious about your claim that current regulation by these things is poor. James, why not try some measurements? Both current and voltage, into (say) either a matched halogen bulb or a power resistor. Give us the results. http://www.jim-easterbrook.me.uk/cyc...o_limiter.html JS. |
#4
|
|||
|
|||
When do blinking lights become just plain annoying?
On Mar 22, 5:08*pm, James wrote:
Frank Krygowski wrote: On Mar 22, 1:40 am, James wrote: There is some, albeit poor, current regulation by most bicycle alternators, but not voltage regulation as you know. I'm curious about your claim that current regulation by these things is poor. Look at the output from a semiconductor voltage regulator. *The output may be within 0.1 or 0.01% of the desired output voltage. But you don't need anything like that precision to run a halogen headlamp. Hell, your car's voltage regulator isn't that precise. I'm afraid you're back to your previous thinking - that any minuscule "improvement" in anything relating to bicycles is absolutely critical. You're like the student who puts a tolerance of 0.001" on the diameter of a hammer handle! - Frank Krygowski |
#5
|
|||
|
|||
When do blinking lights become just plain annoying?
On Mar 22, 5:12*pm, James wrote:
Frank Krygowski wrote: On Mar 22, 1:40 am, James wrote: There is some, albeit poor, current regulation by most bicycle alternators, but not voltage regulation as you know. I'm curious about your claim that current regulation by these things is poor. James, why not try some measurements? *Both current and voltage, into (say) either a matched halogen bulb or a power resistor. *Give us the results. http://www.jim-easterbrook.me.uk/cyc...o_limiter.html Nice try, but: He didn't give measurements of the current nor the unclipped voltage vs. road speed, which is what I suggested you measure. He's assumed certain values of unclipped voltage and approximately computed the corresponding clipped voltage, based on his computed generator inductance. Here are the actual measurements I got, again, using a lab-grade true RMS meter, with a bog-standard Union bottle generator: 8 mph 10 12 14 16 18 20 22 24 26 mph 5.40 5.80 6.00 6.16 6.30 6.36 6.41 6.45 6.48 6.48 Volts The general rule of thumb is that halogen bulbs operate best within 10% of their rated voltage. Here are the current readings we got, in amperes, at those same speeds: 0.44 0.47 0.49 0.51 0.52 0.52 0.53 0.53 0.53 0.53 From 12 mph to 26 mph, current is constant within a few percent. Now: Do you own a meter? Why not take some measurements to see if you match our results? It's really not that hard! - Frank Krygowski |
#6
|
|||
|
|||
When do blinking lights become just plain annoying?
On Mar 22, 6:30*pm, Frank Krygowski wrote:
On Mar 22, 5:12*pm, James wrote: Frank Krygowski wrote: On Mar 22, 1:40 am, James wrote: There is some, albeit poor, current regulation by most bicycle alternators, but not voltage regulation as you know. I'm curious about your claim that current regulation by these things is poor. James, why not try some measurements? *Both current and voltage, into (say) either a matched halogen bulb or a power resistor. *Give us the results. http://www.jim-easterbrook.me.uk/cyc...o_limiter.html Nice try, but: *He didn't give measurements of the current nor the unclipped voltage vs. road speed, which is what I suggested you measure. *He's assumed certain values of unclipped voltage and approximately computed the corresponding clipped voltage, based on his computed generator inductance. Oh, another serious problem with Easterbrook's page: If you install zeners, you don't put them in series back to back, as he claimed. You put them in parallel, facing opposite directions. In series, you'd get no current flow until the voltage exceeded the zener voltage (plus the forward diode voltage) which is vaguely opposite of what you want. Looks like Easterbrook didn't do measurements either. - Frank Krygowski |
#7
|
|||
|
|||
When do blinking lights become just plain annoying?
Frank Krygowski wrote:
On Mar 22, 5:08 pm, James wrote: Frank Krygowski wrote: On Mar 22, 1:40 am, James wrote: There is some, albeit poor, current regulation by most bicycle alternators, but not voltage regulation as you know. I'm curious about your claim that current regulation by these things is poor. Look at the output from a semiconductor voltage regulator. The output may be within 0.1 or 0.01% of the desired output voltage. But you don't need anything like that precision to run a halogen headlamp. Hell, your car's voltage regulator isn't that precise. Obviously. The voltage regulator on a car alternator is probably not that precise, but far more precise than the regulation provided by the internal inductance of the bicycle dynamo. I expect a car alternator regulator to regulate the output voltage to about 2%. Most even have temperature compensation so that the battery receives less float voltage as the temperature increases in the engine bay. Hence, by comparison, I'd say the bicycle dynamo regulation is poor. Whether or not the bicycle dynamo regulation is sufficient to safely run a halogen headlamp without external regulation, depends on the nominal rating of the dynamo, the regulation of the dynamo in question, how the halogen bulb is rating, and the wires used to deliver power too it. I recall someone advising me to use heavy cables to power spotlights on my car, and a relay to switch them. The idea being that the lower voltage drop to the bulb would make them brighter and whiter. Certainly this was the effect, however the frequency of replacing bulbs also increased significantly. I doubt that there was a 10% (1 volt perhaps) increase in voltage, but the burn out rate of the bulbs was markedly increased. I'm afraid you're back to your previous thinking - that any minuscule "improvement" in anything relating to bicycles is absolutely critical. You're like the student who puts a tolerance of 0.001" on the diameter of a hammer handle! I'm afraid you're back to your old tricks too. No wonder you annoy people. JS. |
#8
|
|||
|
|||
When do blinking lights become just plain annoying?
On 3/22/2011 2:12 PM, James wrote:
Frank Krygowski wrote: On Mar 22, 1:40 am, James wrote: There is some, albeit poor, current regulation by most bicycle alternators, but not voltage regulation as you know. I'm curious about your claim that current regulation by these things is poor. James, why not try some measurements? Both current and voltage, into (say) either a matched halogen bulb or a power resistor. Give us the results. http://www.jim-easterbrook.me.uk/cyc...o_limiter.html It's so wasteful to use a linear voltage regulator like a zener diode. You're just bleeding off the extra power as heat. A DC to DC switching regulator is more efficient, but you have the losses of the AC to DC conversion in addition to the losses in the switcher. The LED lights are ideal, the faster you ride the more power you generate and the brighter the lights (this is for proper LED lamps, not just attaching LEDs directly to the dynamo. Most of the MR16 Cree LED lamps are rated at 8-15V AC or DC, but in fact will operate at lower voltages, so they are suitable for dynamo use. While you're probably slightly better off with one of the lamps like http://www.ledshoponline.com/mr16_t-type_cree_bike_light.htm or http://www.ledshoponline.com/high_power_mr16_led_10deg.htm, the reality is that even the lower cost MR16 lamps are significantly better than equivalent wattage halogen lamps, i.e. http://www.dealextreme.com/p/mr16-3w-cree-q5-180-lumen-white-led-light-bulb-12v-dc-15559. |
#9
|
|||
|
|||
When do blinking lights become just plain annoying?
Frank Krygowski wrote:
On Mar 22, 5:12 pm, James wrote: Frank Krygowski wrote: On Mar 22, 1:40 am, James wrote: There is some, albeit poor, current regulation by most bicycle alternators, but not voltage regulation as you know. I'm curious about your claim that current regulation by these things is poor. James, why not try some measurements? Both current and voltage, into (say) either a matched halogen bulb or a power resistor. Give us the results. http://www.jim-easterbrook.me.uk/cyc...o_limiter.html Nice try, but: He didn't give measurements of the current nor the unclipped voltage vs. road speed, which is what I suggested you measure. He's assumed certain values of unclipped voltage and approximately computed the corresponding clipped voltage, based on his computed generator inductance. Here are the actual measurements I got, again, using a lab-grade true RMS meter, with a bog-standard Union bottle generator: 8 mph 10 12 14 16 18 20 22 24 26 mph 5.40 5.80 6.00 6.16 6.30 6.36 6.41 6.45 6.48 6.48 Volts The general rule of thumb is that halogen bulbs operate best within 10% of their rated voltage. Here are the current readings we got, in amperes, at those same speeds: 0.44 0.47 0.49 0.51 0.52 0.52 0.53 0.53 0.53 0.53 From 12 mph to 26 mph, current is constant within a few percent. Now: Do you own a meter? Why not take some measurements to see if you match our results? It's really not that hard! Not personally. I could perhaps borrow one from where I work. What load did you use? This was from one dynamo, and may not be representative of the one I have and prefer to use, or of other Union dynamos. Jim does say that he assumed the power output at 10mph is 3W, where as for your results it is only 2.7W. As Jim actually performed this experiment, and that he says "It is no wonder that bulbs blow so often." I can only assume he was blowing globes regularly and decided he needed to do something about it. JS. |
#10
|
|||
|
|||
When do blinking lights become just plain annoying?
On 3/22/2011 3:52 PM, James wrote:
Whether or not the bicycle dynamo regulation is sufficient to safely run a halogen headlamp without external regulation, depends on the nominal rating of the dynamo, the regulation of the dynamo in question, how the halogen bulb is rating, and the wires used to deliver power too it. Actually the wires make little difference, since any wire of a heavy enough gauge not to easily break can carry 500mA. The problem with bicycle dynamos is that while the current doesn't vary much, the voltage does. 6V versus 9V at 500mA doesn't matter much to a good LED lamp, but it matters a lot to an HS3. Hence any decent headlamp that uses an HS3 bulb will have over-voltage protection built in. That protection only costs a few cents in terms of components. |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Training or Plain Riding? | Tom Kunich | Racing | 286 | December 17th 08 02:25 PM |
Blinking Lights good this time of the year! | Sir Ridesalot | General | 54 | November 6th 07 11:54 PM |
Blinking Lights good this time of the year! | [email protected] | Techniques | 26 | October 31st 07 03:48 AM |
just plain fun (informative, too!) | Birchy | Rides | 0 | December 21st 04 11:28 PM |
Break lights turn lights and handle bar lights | Truepurple | Techniques | 30 | November 17th 03 04:02 AM |