Home |
Search |
Today's Posts |
#7
|
|||
|
|||
High brightness LEDs?
On Fri, 28 Nov 2014 08:50:09 -0500, Scott Dorsey wrote:
gareth wrote: These LED replacements for 240V mains lamps; if one were to open them, would one find a high voltage regulator suitable for some of our valve experiments and repairs? You might find a little constant current supply, but my guess is that you'd just find a big dropping resistor. That configuration would result in most of the power being wasted as heat, but it would still produce less heat than an incandescent and be brighter. If you want a high voltage regulator, a TIP50 transistor and a high voltage zener (or a string of low voltage zeners) will fix you right up. The TIP50 is comparatively easy to damage, but if you don't hook it up backwards or something it will be very, very reliable. Not expensive. Think of the TIP50 as a 5080 replacement with a lot more gain and better transconductance in the bargain. If you want a high voltage switcher, on the other hand, look at the Linear Technology chips intended for LCD backlight inverters. There are some great Jim Williams applications notes. --scott The regulators in LED lamps are constant current types, not constant voltage. They also have some sort of step-down circuit because the LED needs a lot more current than what you would want to draw from the AC lines. Common power LED currents are in the neighborhood of 350 and 700 mA. Some very small LED lamps, Christmas light size, use capacitors to limit the current. Jim Mueller -- Jim Mueller To get my real email address, replace wrongname with dadoheadman. Then replace nospam with fastmail. Lastly, replace com with us. |
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Forum | |||
OT? Satellit 800 Alignment info or Display brightness mod | Shortwave | |||
LEDs | Shortwave | |||
Pulsing LEDs for higher efficiency | Homebrew | |||
Some Radio Pics LEDs | Shortwave | |||
FS Ad - Electronic Components including TIL311 Hex Displays - LEDs - TTL Chips | Homebrew |