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Re: DT-02 Grasshopper redux 12 years 4 months ago #4562

...
why connect up 3? what resistors are you using? i connrcted 2 up to a 9v battery and without a resistor they blew instantly


Three because I was taking a guess at the forward voltage of the LEDs - I assumed they'd be around 3V - so 9V / 3fV = 3 ... so 2 LEDs wired in series would go pop, 3 wired in series would be ok :)

Resistors for that bodge = none ...


I think you're still worried about what resistors you've used on your car - so looking back at the LED specs you posted, they have a maximum forward voltage of 4V, and your power source was 5.0V ... so the resistor needed (assuming you use one resistor per LED, and all the LEDs are wired indivually - i.e. in parallel) is:

((Supply V - Forward V) / current draw in mA) * 1000
or ((5-4)/20))*1000
or (1/20)*1000
= 0.05 * 1000
= 50 ohm resistor

or, if you assume a more normal fV of 3 instead of 4, 100 ohms ...

Or if you wanted to use just one resistor & split the output from that 4 ways, the 20mA above would become 80mA - meaning you'd need a 12.5 ohm resistor ...

:)

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Re: DT-02 Grasshopper redux 12 years 4 months ago #4563

ok now im confused.com totally. i have only wired up 2 LED's for now as i am not convinced i want to drill holes in the front of the chassis to make it 4 as i cant see them shedding much forward light. i bought the 10ohm resistors as recommended in a previous post and as my last post states they run fine, and not hot so i am gonna stick with it for now unless i decide to add the other 2 on the front, then i will have a rethink

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Re: DT-02 Grasshopper redux 12 years 4 months ago #4597

My cunning plan to make the lenses didn't work - heating them up with a hot arir gun & using a small paperweight to get the shape worked - but they shrank unevenly & the scored lines disappeared :(

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Re: DT-02 Grasshopper redux 12 years 4 months ago #4598



I may not have got the dome effect I wanted on the lens, but overall I'm fairly chuffed with that :)
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Re: DT-02 Grasshopper redux 12 years 4 months ago #4602

That looks absolutely brilliant. B)

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Re: DT-02 Grasshopper redux 12 years 4 months ago #4604

looks very cool jonny, you have the retro (heehee) look where as i have gone for the modern HID look, both look fab

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Re: DT-02 Grasshopper redux 12 years 3 months ago #4614

Wiring for LEDs - I thought tapping into the RX was tidiest ... used the plastic bits from ball links as nuts for the lights as the machine screws I epoxied in weren't long enough - but it did give a handy place to secure the wiring ...




Top view ...




side view - proportions don't look as good as the original Grasshopper - not enough in front of the front wheels (could be fixed by using the old skool bumper?) ...




... and way too much hanging out the rear ... If I were to do this again, I think I'd probably extend the body in the middle & make it a two seater ...



Underside ...




Lights do a fantastic job of lighting up the back of the front shock towers :whistle:




I have a sheet of re-re Grasshopper stickers I could put on - unusually, the precutting process was actually fairly accurate on that sheet ... but I'm undecided about using them - I like the look as it is, but the paintwork is a bit poor & could use the distraction ...
The following user(s) Liked this: CrummeyGrasshopper

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Last edit: by Jonny Retro.

Re: DT-02 Grasshopper redux 12 years 3 months ago #4616

It's starting to look the bomb again. That is one cool Grasshopper. B)

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Re: DT-02 Grasshopper redux 12 years 3 months ago #4619

Bit the bullet & put the stickers on ... everything is where it should be apart from on the rear wing - I moved the grasshopper to on top of the power bulge & doubled up the text ...




... the slightly concave "reflector" bowls & hatched lenses do quite a good job of diffusing the lights into a useable headlight pattern ... which is then totally ruined by the shock towers ...




Anyway - another car to the "done" line :)
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Re: DT-02 Grasshopper redux 12 years 3 months ago #4622

The Grasshopper builds on TB are certainly a source of inspiration.
I think I should do a Hornet though to keep it a bit original. ;)

Wondering how the body posts were done on this one exactly...

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