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App note: How current and power relates to losses and temperature rise on inductors and transformers

อาทิตย์, 11/04/2018 - 20:00

Coilcraft’s app note on temperature rise due to losses on inductors and transformers. Link here (PDF)

Core and winding losses in inductors and transformers cause a temperature rise whenever current flows through a winding. These losses are limited either by the allowed total loss for the application (power budget) or the maximum allowable temperature rise.

For example, many Coilcraft products are designed for an 85°C ambient environment and a 40°C temperature rise implying a maximum part temperature of +125°C. In general, the maximum allowed part temperature is the maximum ambient temperature plus temperature rise. If the losses that result in the maximum allowed part temperature meet the power budget limits, the component is considered acceptable for the application.

Free PCB coupon via Facebook to 2 random commenters

เสาร์, 11/03/2018 - 06:33

Every Friday we give away some extra PCBs via Facebook. This post was announced on Facebook, and on Monday we’ll send coupon codes to two random commenters. The coupon code usually go to Facebook ‘Other’ Messages Folder . More PCBs via Twitter on Tuesday and the blog every Sunday. Don’t forget there’s free PCBs three times every week:

Some stuff:

  • Yes, we’ll mail it anywhere in the world!
  • We’ll contact you via Facebook with a coupon code for the PCB drawer.
  • Limit one PCB per address per month, please.
  • Like everything else on this site, PCBs are offered without warranty.

We try to stagger free PCB posts so every time zone has a chance to participate, but the best way to see it first is to subscribe to the RSS feed, follow us on Twitter, or like us on Facebook.

N6QW Heathkit SSB transceiver

เสาร์, 11/03/2018 - 06:30

Pete Juliano, N6QW,  has a nice build log on his newest version Heathkit 40M SSB Transceiver:

What are you thinking — I am not trying to break any world record? My XYL asked me that question today — why are you building another rig? Followed up by a snide comment that I had so many rigs now why do I need another one. Well the answer plain and simple because I can!
For the longest time in the late 60’s early 70’s my success rate with homebrew SSB transceivers was miserable. At that time I lacked the more sophisticated test gear and let’s face it some of the technology wasn’t that great. Crappy Analog VFO’s were high on the list of impediments! I also had to work and to give a fair share of my time to the family — it is that balance thing.
But today that is all changed –better test gear, better technology like Digital VFO’s and a bit more time. The latest project is to demonstrate that some of the components out of boat anchors can indeed be reworked to provide a very modern, very capable rig.

See the full post on N6QW blog.

Check out the video after the break.

Relays (DC): 99.9% less power and latching option

ศุกร์, 11/02/2018 - 05:16

Technovative writes, “The purpose of this article, is to show a simple method to increase the power efficiency, and functionality, of standard DC actuated electromagnetic relay switches.”

Project instructables here.

#FreePCB via Twitter to 2 random RTs

พุธ, 10/31/2018 - 06:34

Every Tuesday we give away two coupons for the free PCB drawer via Twitter. This post was announced on Twitter, and in 24 hours we’ll send coupon codes to two random retweeters. Don’t forget there’s free PCBs three times a every week:

  • Hate Twitter and Facebook? Free PCB Sunday is the classic PCB giveaway. Catch it every Sunday, right here on the blog
  • Tweet-a-PCB Tuesday. Follow us and get boards in 144 characters or less
  • Facebook PCB Friday. Free PCBs will be your friend for the weekend

Some stuff:

  • Yes, we’ll mail it anywhere in the world!
  • Check out how we mail PCBs worldwide video.
  • We’ll contact you via Twitter with a coupon code for the PCB drawer.
  • Limit one PCB per address per month please.
  • Like everything else on this site, PCBs are offered without warranty.

We try to stagger free PCB posts so every time zone has a chance to participate, but the best way to see it first is to subscribe to the RSS feed, follow us on Twitter, or like us on Facebook.

Battery monitor on a automotive relay form factor

พุธ, 10/31/2018 - 06:32

Jesus Echavarria made this battery monitor and wrote a post on his blog detailing its assembly:

Here’s one of the design I do last year for a client. He wants to measure the voltage of a car battery and set a couple of alarms when voltage falls below a defined values. Also, he wants to put the device in the relay box of the car, so the design needs to have a relay form factor to easy integration. So, after a couple of iterations, here’s the final design of the battery monitor.

Via Designing Electronics in Spain.

ICSP switch box

อังคาร, 10/30/2018 - 06:55

Stynus has published a new build:

For a project I need to program a few microcontrollers in the same circuit. This meant I needed to plug the programmer around on the board a lot.  This got annoying very fast. Therefore I decided to make a switch box. In my junk pile I found an old switch of a, parallel port switch. This has 4 positions and a lot of contacts. For the ICSP I only need 3. However in some circuits the supply voltage is not common. Hence, I chose to also switch the power supply connections.  For the connections to the circuit boards I used DIN connectors, for the simple reason I have lots of these.

See the full post on ElektronicaStynus blog.