Hmmm, Restriction done, but did it work?

[Jayneflakes]

Hmmm, this mechanics lark is getting tricky now.



Yes it was a tad cold... Thankfully Carol lent me her Generator and I had light, music and heat in the garage and had a lot of fun.

I have fitted the Flush fit indi's and despite them being coffin shaped, they look pretty cool, although my awful photos do not do them justice.



I put the nice ones that I bought before on the rear now and I think that they look really nice, just above the number plate.



I have also fitted the shiny polished bits.




Once in place and with wires still poking out I thought I should check the lights and see if they flash OK. Glad I checked, they flash two or three times faster than they used to, despite the E-Bay guy saying that they were plug and play! Grrrrr.

I am thinking that I must need a resistor in the circuit due to the LED lights needing less power to function, wired in series after the light (on the negative lead) I think, but I have no idea of the level of Resistance needed, any one have any ideas? It can't be more than a couple of hundred Ohms I would imagine, but I may be wrong?

http://cgi.ebay.co.uk/Ballast-resist...item5ad60b3e64

I used these for my LED indicators on my SV.

Expensive but easy. Not sure what value resistor you would need otherwise.

[Dave20046]

Originally Posted by zobers

http://cgi.ebay.co.uk/Ballast-resist...item5ad60b3e64

I used these for my LED indicators on my SV.

Expensive but easy. Not sure what value resistor you would need otherwise.

Just wire the standard bulbs in with the leds if you still have them, same as a ballast imo - if not buy something a similar to the above. If you don't fancy it get a proper led flasher unit, would be easier if you've wired in new led's all round* the bike.



*imperitive

[Jayneflakes]

Originally Posted by Dave20046

Just wire the standard bulbs in with the leds if you still have them, same as a ballast imo - if not buy something a similar to the above. If you don't fancy it get a proper led flasher unit, would be easier if you've wired in new led's all round* the bike.



*imperitive

Good idea

However, I have been doing some research and found this.

Originally Posted by SV Rider.com

LED draws very low current - maybe 20mA
Bulb draws relatively high current - 21W bulb = 1.75Amps

In order to have the relay 'think' that it is supplying a bulb, it needs to flow more current.
The lower the resistance across a voltage source, the higher the current.
Conversely, the higher resistance is, the lower the current will be

The way to have more current is to connect a parallel resistor across the LED, which lowers the net resistance and so increases the current.
Because it's a parallel load, the current through the LED remains unchanged.

Originally Posted by E-Bay Guy

Just connect the positive wire of the indicator to one wire of the resistor and the negative wire to the indicator to the other wire of the resistor using the fittings supplied.

(It will look like you are shorting the indicator out).

Now I have measured the resistance of the indicator lamps which was 0.9 Ohms and by using a bit of maths I show a resistance should be about 1.7 Ohms, so I am thinking that by attaching a 1 Ohm Resistor across the LED Indicator I should be able to slow the flash rate down.

Given that the Ballast Resistors on E-Bay are probably just wound wire resistors with a heat sink, I should imagine I can pick some up for a lot cheaper than these.

For example

10 Watt, 1 Ohm resistor = 48 pence from Maplin.

Would this do the job I need, given that I have filament bulbs on the rear and LED lamps on the front, so a new flasher unit would not work? If this is more than I need, could I just fit a standard metal film resistor which does come in 1.5 Ohms?


I am confused and my brain hurts because I am rubbish at Maths.

[ophic]

Go to HG and buy some resistors from there. They are only about a couple of quid each, and are designed for the job.

The resistor needs to sink 21W - this is quite some current, so little resistors from Maplins won't work - they'll blow up and smell bad.

You can't measure bulbs directly as you have done - the resistance increases as they get hot.

So... 21W, 12V, P=IV, so I=21/12 = 1.75A (assuming negligible current draw from LED indies)

V=IR, R=V/I, 12/1.75=6.86ohm

so you want something of the order of a 21W rated 7ohm resistor, wired in parallel with each LED, so obviously you'll need 2. A slightly higher power rating wouldn't go amiss.

[yorkie_chris]

Maplin sell power resistors too.

If they need to sink 21W (each or per side?), then P = IV and V = IR give R = V^2 / P so that should tell you. Just make sure there's enough power dissapating built in.


Personally I don't like ballasts, seems messy to just waste power. I like solid state relays.

[ophic]

Originally Posted by yorkie_chris

Maplin sell power resistors too.

yup

Originally Posted by yorkie_chris

If they need to sink 21W (each or per side?), then P = IV and V = IR give R = V^2 / P so that should tell you. Just make sure there's enough power dissapating built in.

each

Originally Posted by yorkie_chris

Personally I don't like ballasts, seems messy to just waste power. I like solid state relays.

agreed

[yorkie_chris]

144/42 = 3.5ohm ish Per side or 6.85 per indicator

So IMO put one power resistor between output of relay and ground. Light blue wire IIRC but could be totally wrong... it is feed from relay to handlebar switch anyway.

[Jayneflakes]

Thank you Guys, that is truly very helpful.

Is that more beer I owe you all?
I need to open my own brewery now.

[yorkie_chris]

Good to see a lass actually doing research about how to sort stuff rather than just chatting crap and taking it to garage, then usually whinging about getting ripped off LOL