LED Bulb Efficiency vs. Operating Life...

[server]

On Sun, 22 Jan 2023 16:29:08 -0800 (PST), Three Jeeps
<jjhudak4@gmail.com> wrote:

>For devices that are suppose to last for quite a long time, putting any light emitting devices in series is really stupid - for one of the reasons you point out.

Due to the temperature coefficient LEDs need to be driven by a
constant current source, not by a constant voltage source.

If you want to put multiple LEDs in parallel and feed them with a
constant voltage, you need to put individual series resistors for each
LED, this will limit the individual LED currents.

Putting multiple LEDs in series, a single constant current source is
enough, like a single series resistor.

 

[three_jeeps]

On Monday, January 23, 2023 at 5:51:08 AM UTC-5, upsid...@downunder.com wrote:

On Sun, 22 Jan 2023 16:29:08 -0800 (PST), Three Jeeps
jjhu...@gmail.com> wrote:

For devices that are suppose to last for quite a long time, putting any light emitting devices in series is really stupid - for one of the reasons you point out.
Due to the temperature coefficient LEDs need to be driven by a
constant current source, not by a constant voltage source.

If you want to put multiple LEDs in parallel and feed them with a
constant voltage, you need to put individual series resistors for each
LED, this will limit the individual LED currents.

Putting multiple LEDs in series, a single constant current source is
enough, like a single series resistor.
Right, I know/understand that. Different design approaches and those extra resistors amount to perhaps an extra $0.10 which probably adds $2.00+ to the cost of the final product. Yea gotta produce cheap, cheap, cheap and dupe the unsuspecting public.

I had a colleague many years ago (late 70\'s early 80;s) who worked at Zenith Corp designing cks for tv\'s and other electronic devices. His assignments typically consisted of: here is a circuit for a subsection of a TV...reduce parts count. Sometimes he was given the assignment of developing a new circuit, if his circuit added between $0.04 to 0.05 USD, he went through a \'design review\' and in most cases was told to do it over again with no cost increase. He figures the money he saved went into paying the people that \'handcrafted\' the sets....(there is a joke there if you remember those commercials...)