Photos, videos and docs of .:madworm:., with the keywords: "diode"

Burned LED

nobody@ipernity.com (.:madworm:.) — Sat, 14 May 2011 13:36:42 +0000

.:madworm:. has posted:

Too bad these things always fail shorted.

High-tech charge regulator

nobody@ipernity.com (.:madworm:.) — Sun, 02 Jun 2013 19:19:57 +0000

.:madworm:. has posted:

Oh man... A 3.3 Ohm resistor... You surely do get a whole lot of 'worth' for your money these days.

1N4007 Diode

nobody@ipernity.com (.:madworm:.) — Sun, 02 Jun 2013 19:20:20 +0000

.:madworm:. has posted:

A massive voltage drop of 0.8xx volts at about 300 mA. Shocking!

More than expected

nobody@ipernity.com (.:madworm:.) — Fri, 31 May 2013 18:12:28 +0000

.:madworm:. has posted:

To be honest, I didn't expect to see a smoothng cap in there.

AC stuff + bridge rectifier

nobody@ipernity.com (.:madworm:.) — Fri, 16 Nov 2012 15:16:28 +0000

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Minimalism.

Resistor's new home

nobody@ipernity.com (.:madworm:.) — Tue, 20 Nov 2012 09:44:41 +0000

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Offender removed

nobody@ipernity.com (.:madworm:.) — Tue, 20 Nov 2012 09:44:42 +0000

.:madworm:. has posted:

Patch applied

nobody@ipernity.com (.:madworm:.) — Tue, 20 Nov 2012 15:25:52 +0000

.:madworm:. has posted:

and fully cleaned.

Hopefully fixed - 8 more to go

nobody@ipernity.com (.:madworm:.) — Tue, 20 Nov 2012 09:44:43 +0000

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So far I've managed to kill 5 of these PT4115 LED drivers, and I don't think that I've abused them - at least when compared to what I've done to other devices that survived no problem.

The failure mode is very consistent. Either it stops working altogether (no more switching, output switch permanently open) or the output switch is permanently closed and the LEDs suffer over-current.

Common to both manifestations is that the DIM pin shows unusually low resistance (about 6Ω) to GND. This makes me believe that this pin gets trashed somehow. Therefore I will test if adding a Zener + dropper resistor will help to protect the chip. Voltage clamping at 5V1 definitely works, so lets see how things go.

Adding a Zener + resistor is the way to go. No more premature demise.

Tinned

nobody@ipernity.com (.:madworm:.) — Tue, 20 Nov 2012 09:44:40 +0000

.:madworm:. has posted:

Mask removed

nobody@ipernity.com (.:madworm:.) — Tue, 20 Nov 2012 09:44:39 +0000

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Waiting resistor

nobody@ipernity.com (.:madworm:.) — Tue, 20 Nov 2012 09:44:39 +0000

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About to cut a trace

nobody@ipernity.com (.:madworm:.) — Tue, 20 Nov 2012 09:44:37 +0000

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Cut trace

nobody@ipernity.com (.:madworm:.) — Tue, 20 Nov 2012 09:44:38 +0000

.:madworm:. has posted:

The result is pretty good. I think I could use an even smaller tool (spear-point drill). Using sub-1mm fluted end-mills can get a bit tricky, especially if they're not of the short and stubby kind. They break quite easily - and cost a lot.

Planned ESD protection

nobody@ipernity.com (.:madworm:.) — Tue, 20 Nov 2012 09:44:37 +0000

.:madworm:. has posted:

1k dropper resistor + 5V1 Zener diode BZX84C5V1.

PT4115 driver - modded

nobody@ipernity.com (.:madworm:.) — Mon, 02 Jan 2012 19:25:02 +0000

.:madworm:. has posted:

I've added a signal wire going to the 'dim' pin and wires getting the rectified voltage.

Diode bugfix

nobody@ipernity.com (.:madworm:.) — Thu, 21 Jun 2012 09:16:32 +0000

.:madworm:. has posted:

Not ideal (free-standing TO-220), but tolerable for a bug-fix. The diode's characteristics are quite good.

Datasheet

Diode bugfix

nobody@ipernity.com (.:madworm:.) — Thu, 21 Jun 2012 09:16:32 +0000

.:madworm:. has posted:

Not ideal (free-standing TO-220), but tolerable for a bug-fix. The diode's characteristics are quite good.