What is a "tuning capacitor" and what does it do here?

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The section continues with another way of building the same thing, using two capacitors instead of the single "tuning capacitor" shown in the first example. It raises additional questions. How is the circuit acting now? And what is the purpose of resistor R1? I don't understand what the author means when he writes that this resistor "biases" C2 and C3.

Help is appreciated - thank you!

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>>1214337
I think C2 'tunes away' the series inductance (L) of the generator for a certain frequency (i.e. speed) leaving only the series resistance (R). In circuit 6 C2 is replaced with two capacitors (of twice the capacity) wired in series such that it acts as a non-polarized cap. R1 is connected to the positive output and ensures that none of the two caps in series can get charged in reverse.

The acoustic analog would be a tuned (and correctly damped) bass-boost loudspeaker cabinet.

Why not save us all alot of bs and use this:

http://www.falstad.com/circuit/

Then post results.

just do it

>>1214411
This kind of makes sense. It gives me a direction to investigate further, which is more important. Thanks!

>>1214710
I had no idea this existed. This is amazing. Thank you.

>>1214745
I am. Reason I want to understand the mechanics of the circuit is because in the future I want to add a USB connection to this so I can charge my phone from my bike as well, and know how to do that without breaking my phone.

>>1214411
This guy gets it.

>>1214332
The change in speed vs power comes from the changing frequency coming out of the dynamo, at lower frequencies the dynamo's impedance from the inductance is low, the impedance from the capacitor is high, as speed ramps up so does the frequency, so the impedance from the inductance rises and the capacitor falls, voltage induced on the dynamo also rises, so picking the cap appropriately can balance out these effects to give the smoother speed in vs power out curve you see there.

>>1214773
>Reason I want to understand the mechanics of the circuit is because in the future I want to add a USB connection to this so I can charge my phone from my bike as well, and know how to do that without breaking my phone.

Protip: Get a car charger (DC-DC converter with 5v output) and wire that. Also charge a powerbank and use that to charge your phone. Having your phone out and about while the bike is going is a recipe for accident.

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>>1214773
The simple solution for adding battery and 5V would be to use an off the shelf power bank. Run your headlight off the power bank too.

>>1214831
I actually already bought one of those car chargers with that idea in mind. Nice to have the confirmation that it will work. And yes, I wasn't going to go into the gory details, but I have a small radio that mounts to the bike that also has an USB-out for phone charging. So the plan was to charge the radio battery from the dynamo and charge the phone from the radio battery. Having the phone out on the bike is no problem, because I have a handlebar mount for it. I don't text and ride, but I do use it for navigation. I like to take long bike trips to go camping or just sightsee.

>>1214969
With 3w at 6v its pointless.

That's around 1/2 amp no load on the generator. You'll never actually charge the phone with the led in play. Even with a power bank.

I'd go with a minimum 10w. That way you could at least get 1/2 amp for the phone and the rest for everything else.

That tank circuit is only to optimize the led. You won't need it with a simple rectifier/regulator to the bank.

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>>1214969
>one of those car chargers
Be sure to get one that can handle 24V, efficiency will be slightly better than at 12V. You will need to limit the output of the dynamo anyway because when the battery is fully charged you have an (almost) open loop situation and the dynamo output voltage will increase (see pic). The most robust way to do that is a MOV (metal oxide varistor) directly in parallel to the dynamo. They are cheap and are available for 12V and 24V.
>charge the radio battery from the dynamo and charge the phone from the radio battery
Sounds good to me. How do you charge the radio? Maybe you don't need the car charger at all. The less complex the better. Don't forget that all that stuff has to be waterproof, including plugs and contacts. I'm currently looking into cheap buck-boost regulators available at ali to keep my VHF/UHF transceiver charged while 'on the road'.

>>1214332
i dunno wtf you guys in this thread are on about but this is just a bridge rectifier and a smoothing cap.
there is no 'tuning' here.

assuming sinusodal input and that the cap is big enough to smooth the whole period the voltage will be increased by a factor of the square root of 2.

6*1.41 = just shy of 8.5v
however, there will be a forward voltage drop in the diodes so assume 1v loss if using regular Si diodes or about 0.5 if using low forward voltage diodes like schottkey diodes.
Si drop about 0.4-5v while good schottkeys drop, 0.2-3v. but remember that two diodes conduct at all times so its twice the drop.


remember that running LEDs with no currentlimiting is generally a bad idea.
some powerLEDs can deal, but i would read the datasheet.
if its some fixed car light i would assume they are built in.

this should have been posted in /ohm/ tbqh

>>1216525
Circuit 2 is. Not circuit 5.

Its fucking stupid if it can't handle the wattage of an led and a fone. All he needs is a bigger dynamo and a bridge.

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>>1216525
>>1216627
Ignorance is _not_ strength.

>>1216689
You can't get more watts out than it's rated for and a tank circuit for sure would help but why needlessly complicate? Do you paint flames on the enclosure after he did all that too?

I dunno what the fuckin point is. Get a dynamo sized for the application and after rectification you're good.

What's the point of cruising along after doing all that and you can't provide 500ma to your fone with the lamp on?

And if you were gonna do all that and have a bike with a circuit on it I wouldn't fuck around with a shitty little tank forcing me to pedal for light . Id get a big fucking cap I can charge all fuckin day which should provide me phone and Headlight services generating or not. Or quick charge.

If you're gonna stick your dick into this don't just put in the tip. Bury it to the onion.

>>1216693
How does your 10 W dynamo look like?

>>1217126
Get all kinds even in the hub

https://www.alibaba.com/showroom/bicycle-dynamo-10w.html

>>1217174
Obfuscation. There are 10W e-bike hub motors (weight 2kg) but not a single 10W hub dynamo. They simply do not exist. The reason should be obvious to any cyclist.

>>1217722
https://m.alibaba.com/product/60642727593/16-28-hub-dynamo-with-ECM.html?subject=16--28--hub--dynamo--with--ECM&spm=a2700.7724857.main07.39.591b5a3wViNJA&detailId=60642727593&redirect=1

W/e you say anon.

Standard size is 6w of course. It's just a harder sell in Americuck cause people are too fat to pedal that load.

Personally I'd set it up so the electrical load engages only after a specific speed, and/or regulate it. I was going to try this myself but then I moved and gave the bike away. Tbh it's the only reason why I even know about this. Now I just burn gas like normal ppl.