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Jeroen W. Pluimers on .NET, C#, Delphi, databases, and personal interests

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Archive for the ‘Hardware Development’ Category

MeanWell Mini Switching Power Supplies May Be Useful for Development Boards

Posted by jpluimers on 2019/11/13

Great power supplies that provide a very stable power source and are adjustable too: [WayBackMeanWell Mini Switching Power Supplies May Be Useful for Development Boards

Via: [WayBack] Tiny Meanwell switch mode power supplies that should provide a good (i.e. reliable) power source for development boards. https://www.cnx-software.com/2… – Jean-Luc Aufranc – Google+

–jeroen

Posted in Development, Hardware Development | 1 Comment »

Blocklist Collection ¦ Firebog

Posted by jpluimers on 2019/10/25

via gitter.im/pi-hole/pi-hole: [WayBack] Blocklist Collection ¦ Firebog

Pi-hole compatible blocklists for you to have a more enjoyable online presence

Thanks Mark Drobnak @Mcat12 for suggesting this.

–jeroen

Posted in LifeHacker, Power User, Raspberry Pi | Leave a Comment »

Fastener Reference Cheat Sheets, by @pighixxx | #ManufacturingMonday

Posted by jpluimers on 2019/10/04

[WayBackFastener Reference Cheat Sheets, by @pighixxx | #ManufacturingMonday

From pan flange to button washer, from socket cap to trim screw heads, not to mention threading types and drive head options, every workbench and workshop should have this fastener reference guide …

via:

–jeroen

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Skin effect – Wikipedia

Posted by jpluimers on 2019/09/23

Skin effect – Wikipedia:

Skin effect is the tendency of an alternating electric current (AC) to become distributed within a conductorsuch that the current density is largest near the surface of the conductor, and decreases with greater depths in the conductor. …

At high frequencies the skin depth becomes much smaller. … Because the interior of a large conductor carries so little of the current, tubular conductors such as pipe can be used to save weight and cost.

Via [WayBack] Odd: “copper” central lead of antenna cable attracted by magnetic screwdriver tip. – Jeroen Wiert Pluimers – Google+

–jeroen

 

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LED Voltage Drops

Posted by jpluimers on 2019/09/19

[WayBackDangerous Prototypes: Basic Light Emitting Diode guide – Voltage drop or forward voltage has a nice table of common LED types:

You can also measure them yourself using most multi-meters have setting for that as described in [WayBack] Easy way to figure out a LED’s Vf in order to pick an appropriate resistor – Electrical Engineering Stack Exchange

You can also measure yourself, but my Proster VC99 multi-meter (cheap, but functions well, see for instance the review in [WayBack] MagPi issue 43) can measure voltage drop, so I’ve measured some LEDs from old PC cases:

  • Red: 1.8 V
  • Yellow: 1.8 V
  • Green: 1.8 V
  • Blue: does not measure

Given that they all have the same voltage drop, I made the below table with some resistor values to get the same current through them on various voltages (3.3V, 5V and 12V) based on Standard resistor values.

Note anything less than 20mA of current usually is OK (though 20mA often is on the bright side).

LED Colour Voltage drop (Vf) Total Voltage Remaining Voltage Resistance Ω Current mA Power mW
Any 1.8 5 3.2 220 14.55 46.55
Any 1.8 12 10.2 680 15.00 153.00
Any 1.8 3.3 1.5 100 15.00 22.50
Any 1.8 5 3.2 330 9.70 31.03
Any 1.8 12 10.2 1000 10.20 104.04
Any 1.8 3.3 1.5 150 10.00 15.00
Any 1.8 5 3.2 470 6.81 21.79
Any 1.8 12 10.2 1500 6.80 69.36
Any 1.8 3.3 1.5 220 6.82 10.23

Background for doing these calculations:

–jeroen

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