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Resistors already in place? Strings of 3 and 4 LEDs? Sounds like you're trying to build something that's nothing like the schematic you posted.TuscanT said:actually you can.
the leds i am using is a cluster of LED from the 2002 onwards range rover tail light. they are aranged in a pentigon shape using a total of 19 LEDs. with resistors already in place. The leds are arranged in strings of 3 and 4 leds with the middle being a row of 5. iv retrofited the unit into my tail lights. they work and light up fine as a brake light. but not as a tail/brake as i want. i just need to find a suitable circuit to make, if anyone can suggest a schematic that i can use that would be great.
mramos1 said:google for tail brake light led circuits
Here is one of 177,000 hits on the search.
https://www.redcircuits.com/Page85.htm like your with NPNs.
The reason goes back MUCH further than public buses, it's not a financial reason. No one has still explained why other countries drive on the right though?.
TuscanT said:
you obviously havent looked at my orignal post. didnt you think that is the first obvious thing anyone would do to seach google? Do refrain from patronising resposes if you cant be of any constructive help.
That is the orignal schematic i posted. and it is not suited for the application that i am using it for.
TuscanT said:
ill have a look into PWM as you mentioned tho. Thanks
Boncuk said:Hi TuscanT,
back to the original thread:
This circuit works with PWM. (Frequency ~ 1.8KHz) If the brake pedal is not depressed (S1 open) the duty cycle is 50%. You can increase it by changing the value of R5 to a smaller value if the LEDs are too dim.
It's not legal in the UK to have flashing tail lights.
You can interpret flashing various ways, but LEDs have a response time of nanoseconds, so the light will be turning on and off.
We aren't offering much useful information to the OP. He has a pre-built stoplight LED module and wants it to operate from the tail light circuit at reduced brightness. The solutions offered seem to ignore this.
It's probably also desired to use existing vehicle wiring (one side grounded without much freedom to modify).
To accomplish what you want, put a diode in series with each supply line so that they don't feed one another. (If it's negative ground, that would be connect the cathodes together.) In the tail light circuit, add a series resistor of a value that produces the desired (reduced) brightness.
Boncuk said:I think you don't consider your TV a flash light, although the lines are drawn in fast sequence.
Of course will the LEDS been turned on and off, but the human eye is too slow to follow the switching. So a PWM-controlled LED isn't a flashing light.
There is no other way to interprete flashing as an obvious flashing with a distinct off and on time. The "flashing" at a speed of several KHz is recongnized as a steady light.
Diver300 said:If car lights were modulated at several kHz, the modulation wouldn't be visible. However a lot of cars modulate at 100 Hz and they are distinctly visible, and annoying.
[FONT="]mneary said:To accomplish what you want, put a diode in series with each supply line so that they don't feed one another. (If it's negative ground, that would be connect the cathodes together.) In the tail light circuit, add a series resistor of a value that produces the desired (reduced) brightness.