Logic switching of 205v

[dan_fritz]

Hello,

I'm busy with a electronics project and right now I'm looking for a part to switch 205v DC with my micro controller. I know how to use a npn transistor as a switch and I would like to use the same technique but now for 205v DC.

I need the 205v DC for driving a series of leds in a decoration, I've removed the basic controller (simple thing that has 8 different modes) and measured how many volts were required to turn the leds on, giving the 205v DC.

I've done some googeling but really couldn't figure it out, right now I have my rectifier bridge + capacitor and voltage divider to give the 205v DC. So I need a part/circuit that can help me with this.

Thanks alot!

 

[CDRIVE]

Use an OptoIsolator. The uC drives the LED section and the NPN PhotoTransistor section drives the base or gate of a HV NPN or FET respectively.

 

[dan_fritz]

Use an OptoIsolator. The uC drives the LED section and the NPN PhotoTransistor section drives the base or gate of a HV NPN or FET respectively.

Oke thanks, any idea what kind of NPN or FET I could use?

 

[CDRIVE]

I'm sure other members can suggest others but I found these..
http://www.ebay.com/itm/TIP50-HV-NPN-Transistor-400-VCE-1A-TO-220-Lot-10-/220741396856

 

[CDRIVE]

You didn't state if these were high current LEDs or not but here's another HV NPN.
http://www.digikey.co.uk/scripts/Dk...earch_go&lang=en&keywords=ZTX458-ND&x=15&y=18

 

[dan_fritz]

You didn't state if these were high current LEDs or not but here's another HV NPN.
http://www.digikey.co.uk/scripts/Dk...earch_go&lang=en&keywords=ZTX458-ND&x=15&y=18

thanks it are leds in a x-mas decoration, the first couple once have a resistor, but I think it are just normal leds placed in serie

 

[CDRIVE]

thanks it are leds in a x-mas decoration, the first couple once have a resistor, but I think it are just normal leds placed in serie

Then we're talking 20mA LEDs. That means the transistor Ice requirements will be low. Just make sure it's saturated well.

 

[dan_fritz]

Use an OptoIsolator. The uC drives the LED section and the NPN PhotoTransistor section drives the base or gate of a HV NPN or FET respectively.

I've bought 4N25 optoisolator, now I see that the Collector Emmitter breakdown voltage is rated ad 70V, I'm a bit confused, Is this a problem for my application or do I need another one?

Thanks!

 

[CDRIVE]

I've bought 4N25 optoisolator, now I see that the Collector Emmitter breakdown voltage is rated ad 70V, I'm a bit confused, Is this a problem for my application or do I need another one?

Thanks!

Use an OptoIsolator. The uC drives the LED section and the NPN PhotoTransistor section drives the base or gate of a HV NPN or FET respectively.

Do you understand this?

Edit: Heading out with the wife for a sandwich Cubano and then to the beach. I'll draw it for you later.

 

[dan_fritz]

Do you understand this?

Edit: Heading out with the wife for a sandwich Cubano and then to the beach. I'll draw it for you later.

Totally forgot about the HV NPN omg, thanks a lot wow,

A schematic would help me a lot (I should draw one myself!)

Thanks!

 

[davenn]

I'm still trying to figure out why you are using 205VDC to feed a bunch of LEDS ??

seems somewhat excessive

Dave

 

[dan_fritz]

I'm still trying to figure out why you are using 205VDC to feed a bunch of LEDS ??

seems somewhat excessive

Dave

I've messured the voltage that is being used by the circuit, now I want to reproduce this circuit but control it with my arduino

 

[CDRIVE]

I've messured the voltage that is being used by the circuit, now I want to reproduce this circuit but control it with my arduino

Where are you located that you're using 205V? Is this is an AC Mains voltage?

Btw, if you want to draw the circuit yourself and post it for conformation of correctness that would be good too. That's how we learn.

 

[davenn]

I've messured the voltage that is being used by the circuit, now I want to reproduce this circuit but control it with my arduino

really doesnt seem right
I have several xmas tree led light units, they all run off low voltage 12 - 24VDC
I suspect you need to reconsider how you are powering the LEDs and do it a more efficient way

@CDrive he said 205VDC


Dave

 

[CDRIVE]

@CDrive he said 205VDC


Dave

Yeah Dave, I just back read the posts. He did say DC. I do know that they've been selling 120VAC Christmas tree LED strings in the U.S., imported from China. I've never really investigated the wiring of them though. I've just assumed a diode, limiting resistor and a bunch of 20mA LEDs in series. They don't have a power pack.

Chris

 

[davenn]

...... I do know that they've been selling 120VAC Christmas tree LED strings in the U.S., imported from China. I've never really investigated the wiring of them though. I've just assumed a diode, limiting resistor and a bunch of 20mA LEDs in series. They don't have a power pack.

Chris

ohhh ya gotta love chinese junk huh
all my ones have plugpacks a couple of them even have musical xmas carol tune generators built into the plugpack

D

 

[CDRIVE]

ohhh ya gotta love chinese junk huh
all my ones have plugpacks a couple of them even have musical xmas carol tune generators built into the plugpack

D

Honestly, the first time I saw one of these things was in the engineering dept at work. It was Christmas time and all the departments in the hospital were setting up their decorations. So I walk in machine shop and I see a bunch of coworkers setting this string up on a small Christmas tree sitting atop a work bench. Joe says "Chris, check these LED lights out. We just bought a sh!t load of them for a song!,".So, I'm checking it out and ask.. "Where's the power pack?" Quote: "Power pack?! It doesn't need a power pack. They plug directly into a receptical.... Gee, you guys in BioMed are waaaay over paid" !

On the up side it was fused. Actually, it should be better defined as a non replaceable fused link.

Chris