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Old May 27, 2010, 10:29 AM
It only takes one good idea
dag214's Avatar
Fishers, Indiana
Joined Oct 2004
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Ok electronics question,
I got a great deal (free) on 200 Panasonic caps, 220uf, 100volts. I know I need less than 50 volts, is the 100 volts going to hurt anything when lengthening my battery leads???

Thanks, Dag
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Old May 27, 2010, 10:30 AM
Weathers Good, Gotta Go Fly
Stevenage, Hertfordshire, UK
Joined Jul 2008
385 Posts
I've only recently found this thread, and only skimmed most of it 'cos it's just too big. But all I can say is WOW incredible.
I would never be able to build anything like this I know I don't have the skills but I can dream, and live vicariously through your build. Thank you so much Dag for bringing it to us. By the way my kids are knocked out by it too.
Changing the subject a bit, you've got to love the Kiwis for their front but take a look at Thompson's safety video

Thomson Airways Safety Video 2009 (3 min 29 sec)



Richard
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Old May 27, 2010, 10:32 AM
It only takes one good idea
dag214's Avatar
Fishers, Indiana
Joined Oct 2004
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Quote:
Originally Posted by mike2663 View Post
I always wanted to ask you if you have fooled with helicopters? Just curious. I swore I would never fly them but tried it and got hooked.
Mike
I have always said also I would never own one, but I think I will, I have one of those little counter rotating in-door guys, I have had a blast with it, and late last summer a buddy has some electric chopper and asked if I wanted to fly it, I hovered it and did good, he however was really excited and said I have to get one.

Problem is I always build out-side the box. Who know how crazy I would get with a chopper.

Thanks, Dag
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Old May 27, 2010, 11:07 AM
Tom Bass Park RC Nonconformist
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USA, TX, Houston
Joined Dec 2007
923 Posts
Quote:
Originally Posted by dag214 View Post
I have always said also I would never own one, but I think I will, I have one of those little counter rotating in-door guys, I have had a blast with it, and late last summer a buddy has some electric chopper and asked if I wanted to fly it, I hovered it and did good, he however was really excited and said I have to get one.

Problem is I always build out-side the box. Who know how crazy I would get with a chopper.

Thanks, Dag

The hell with it Dag..

Small Helis are for sissies.. Build one from scratch.. Shall we say, 20 foot rotors?


Come on, You Can Do It!!!
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Old May 27, 2010, 11:33 AM
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Quote:
Originally Posted by dag214 View Post
Ok electronics question,
I got a great deal (free) on 200 Panasonic caps, 220uf, 100volts. I know I need less than 50 volts, is the 100 volts going to hurt anything when lengthening my battery leads???
The voltage overrating will not hurt anything. But get a second and third opinion for reassurance.
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Old May 27, 2010, 01:40 PM
Übung macht den Meister..
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United States, OR, Fairview
Joined Jul 2006
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As near as I can recall, the voltage rating of a cap denotes the voltage beyond which the dielectric would fail. Any voltage below that is good to go, the capacitance value then fitting the required application.

James
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Old May 27, 2010, 01:45 PM
Hey Guys, Watch This.......
mike2663's Avatar
USA, TX, El Paso
Joined Dec 2003
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Quote:
Originally Posted by dag214 View Post
I have always said also I would never own one, but I think I will, I have one of those little counter rotating in-door guys, I have had a blast with it, and late last summer a buddy has some electric chopper and asked if I wanted to fly it, I hovered it and did good, he however was really excited and said I have to get one.

Problem is I always build out-side the box. Who know how crazy I would get with a chopper.

Thanks, Dag
Helis always require "thinking outside the box". There right up your alley. I think you would enjoy the challenge.
Mike
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Old May 27, 2010, 02:14 PM
War Eagle!
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United States, AL, Huntsville
Joined Sep 2006
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oldcoot and Deuce are correct, the voltage listed is their rating, it has nothing to do with what they will 'give' you.

A cap acts as a buffer, think of it as a water tower in a city. If the pressure in the mains drops due to high demand, water flows out of the tower to try and hold the mains at the proper pressure. If the pressure in the mains remains constant, the tower stays topped off.

Think of the 100V rating as the max pressure you could take the water tower to without risk of it leaking or blowing bolts/rivets.

edit:

A note on capacity of a cap.

Per the analogy above, a larger (the uf rating on a cap) water tower will 'hold' the pressure (voltage) for longer. Similarly, it will take longer to 'charge'. In a cap, the same hold true, but when charging a cap, a larger cap can possibly put more demand on your system as it tries to charge.

Caps are great because they can charge and discharge very quickly, this means you can have very high instantaneous currents (ie, you can make a cute little spot welder with a small array of caps the size of your computer mouse) that can be quite dangerous. These caps could pull upwards of 100's of amps on startup when you first plug in your batteries, possibly damaging the connector, so it may be advisable to add a current limiting resistor in parallel. If you are interested in doing it, let me know. I've got a nice picture stored that I found on the forum that explains it very well.
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Old May 27, 2010, 03:02 PM
Übung macht den Meister..
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United States, OR, Fairview
Joined Jul 2006
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For what it's worth, a Leyden Jar (diagram above!) is nothing more than a "fancy" (and fragile? ) capacitor.


When hooked together as shown, you have the equivalent of a battery. Of course, "battery" implies more than one "cell," electrically connected (in series or parallel) to achieve some effect greater than the individual cell can provide... The same term refers to more than one gun employed together, i.e. a howitzer battery.

James (just running off at the mouth, now!)
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Old May 27, 2010, 03:38 PM
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Quote:
A note on capacity of a cap.

Per the analogy above, a larger water tower will 'hold' the pressure for longer. Similarly, it will take longer to 'charge'. In a cap, the same hold true, but when charging a cap, a larger cap can possibly put more demand on your system as it tries to charge.
Might oughta clarify that "larger" in this context refers to its capacitance rating, not voltage rating.
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Old May 27, 2010, 04:59 PM
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Cap Question

Quote:
Originally Posted by oldcoot88 View Post
The voltage overrating will not hurt anything. But get a second and third opinion for reassurance.
Hi Damon,

Glad to see your back on the B-36. I would also be interested in a set of your B-36 plans at half the size, printed if possible. Just let me know the cost.

Regarding the capacitor question, the uF rating refers to the amount of current the cap can store and the voltage rating refers to the maximum voltage the cap will operate under. The higher voltage cap will work fine! The higher the uF rating the higher the current draw (spike) you circuit will handle. As you know the cap is there to prevent you ESC from burning up. The analogy of it being like a water storage tank in a water system is right only it is storing current in your circuit.

Best Regards,

Gary
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Old May 27, 2010, 05:07 PM
I fly, therefore, I crash!!!
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San Jose, CA
Joined Jan 2008
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Hi Dag....

Is there enough room to mount the ESC between the legs of the motor mount, flat on the firewall??? I would think that with the fan on the ESC, that you would have enough cooling???

SteveT
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Old May 27, 2010, 05:27 PM
Registered User
USA, CA, San Bernardino
Joined Oct 2009
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Cap Question

Quote:
Originally Posted by dag214 View Post
Ok electronics question,
I got a great deal (free) on 200 Panasonic caps, 220uf, 100volts. I know I need less than 50 volts, is the 100 volts going to hurt anything when lengthening my battery leads???

Thanks, Dag
Hi Dag,

The voltage is fine but the uF rating seems to be a bit low to me. If it were me, for a 6c battery I would install two 1500uF in parallel and if it is a 5c battery two 2700uF caps in parallel. Install them as close to the ESC as possible on the battery input to the ESC. Regarding the cap uF rating I would double check with the ESC MFG.

Best Regards,

Gary
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Old May 27, 2010, 06:22 PM
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United States, MI, Detroit
Joined Feb 2004
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hey for access to the ESC, what about making "scale" access panels?
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Old May 27, 2010, 06:24 PM
War Eagle!
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United States, AL, Huntsville
Joined Sep 2006
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Quote:
Originally Posted by greeter896 View Post
Hi Dag,

The voltage is fine but the uF rating seems to be a bit low to me. If it were me, for a 6c battery I would install two 1500uF in parallel and if it is a 5c battery two 2700uF caps in parallel. Install them as close to the ESC as possible on the battery input to the ESC. Regarding the cap uF rating I would double check with the ESC MFG.

Best Regards,

Gary

If it is within his skill set, he would be better off using those caps and adding them in parallel to get to the total capacitance that he needs. The smaller caps will likely have a faster response time compared to using fewer, larger caps.
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