Monthly Archives: December 2017

App note: Capacitor selection guidelines on LDOs

via Dangerous Prototypes

an_analog_AN-1099

They are different kind of capacitors, selection for one capacitor varies depending on application. A good read app note from Analog Devices. Link here (PDF)

Capacitors are underrated. They do not have transistor counts in the billions nor do they use the latest submicron fabrication technology. In the minds of many engineers, a capacitor is simply two conductors separated by a dielectric. In short, they are one of the lowliest electronic components.

It is common for engineers to add a few capacitors to solve noise problems. This is because capacitors are widely seen by engineers as a panacea for solving noise related issues. Other than the capacitance and voltage rating, little thought is given to any other parameter. However, like all electronic components, capacitors are not perfect and possess parasitic resistance, inductance, capacitance variation over temperature and voltage bias, and other nonideal properties.

These factors must be considered when selecting a capacitor for many bypassing applications or where the actual value of the capacitor is important. Choosing the wrong capacitor can lead to circuit instability, excessive noise or power dissipation, shortened product life, or unpredictable circuit behavior.

Free PCB Sunday: Pick your PCB

via Dangerous Prototypes

BP-600x373

We go through a lot of prototype PCBs, and end up with lots of extras that we’ll never use. Every Sunday we give away a few PCBs from one of our past or future projects, or a related prototype. Our PCBs are made through Seeed Studio’s Fusion board service. This week two random commenters will get a coupon code for the free PCB drawer tomorrow morning. Pick your own PCB. You get unlimited free PCBs now – finish one and we’ll send you another! Don’t forget there’s free PCBs three times every week:

Some stuff:

  • Yes, we’ll mail it anywhere in the world!
  • Be sure to use a real e-mail in the address field so we can contact you with the coupon.
  • Limit one PCB per address per month please.
  • Like everything else on this site, PCBs are offered without warranty.
  • PCBs are scrap and have no value, due to limited supply it is not possible to replace a board lost in the post

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App note: Linear regulators reverse voltage protection

via Dangerous Prototypes

an_rohm_linearreg_reverse_voltage_appli-e

Various input and output reverse voltage protection method for linear regulators discussed in this app note from ROHM. Link here (PDF)

A linear regulator integrated circuit (IC) is a DC-to-DC buck converter system that reduces a DC supply from higher voltage level to a lower voltage level, thus it requires that the input voltage is always higher than the regulated voltage. Output voltage, however, may become higher than the input voltage under specific situations or circuit configurations, and that reverse voltage and current may cause damage to the IC. A reverse polarity connection or certain inductor components can also cause a polarity reversal between the input and output terminals. This application note provides instructions on reversed voltage polarity protection for ICs.

Want to move heavy loads? We’ve got the linear actuator for you!

via Pololu Blog

We have expanded our selection of Glideforce linear actuators from Concentric International to include their industrial-duty and medium duty series as steps up in power from their light-duty series that we have been offering for many years now.

The medium-duty actuators are available in five different stroke lengths ranging from 4″ to 12″ and with or without feedback potentiometers, and they have a dynamic load rating of 225 lb, which means they can handle twice the load of their light-duty counterparts:

Glideforce Medium-Duty (MD) series of linear actuators with feedback.

Glideforce Medium-Duty (MD) series of linear actuators without feedback.

The industrial-duty actuators are real monsters compared to the medium-duty and light-duty units. The versions with an acme screw drive can handle dynamic loads up to 550 lb, and the versions with a ball screw drive (which is much more efficient than an acme screw) can handle dynamic loads up to a 1000 lb. Each drive option is available in six different stroke lengths ranging from 4″ to 24″ and with or without feedback potentiometers:

The following lets you compare all of our Glideforce linear actuator options:

Actuator
Type
Max
Dynamic
Load
No-Load
Speed
@ 12 V
Current
Draw
@ 12 V
Nominal
Stroke
Length
With Feedback Without Feedback Approx.
Weight
Light-Duty
(LD)
15 kgf
[34 lbs]
4.4 cm/s
[1.7″/s]
1.2 A –
3.2 A
4″ LACT4P-12V-05 LACT4-12V-05 1.3 kg
12″ LACT12P-12V-05 LACT12-12V-05 1.6 kg
50 kgf
[110 lbs]
1.5 cm/s
[0.57″/s]
2″ LACT2P-12V-20 LACT2-12V-20 1.2 kg
4″ LACT4P-12V-20 LACT4-12V-20 1.3 kg
6″ LACT6P-12V-20 LACT6-12V-20 1.4 kg
8″ LACT8P-12V-20 LACT8-12V-20 1.5 kg
10″ LACT10P-12V-20 LACT10-12V-20 1.5 kg
12″ LACT12P-12V-20 LACT12-12V-20 1.6 kg
Medium-Duty
(MD)
100 kgf
[225 lbs]
1.5 cm/s
[0.58″/s]
1.1 A –
4.6 A
4″ MD122004-P MD122004 1.1 kg
6″ MD122006-P MD122006 1.2 kg
8″ MD122008-P MD122008 1.3 kg
10″ MD122010-P MD122010 1.4 kg
12″ MD122012-P MD122012 1.5 kg
Industrial-Duty
(ID)
with Acme
screw drive
250 kgf
[550 lbs]
1.7 cm/s
[0.66″/s]
2.4 A –
13.2 A
4″ LACT4-500APL LACT4-500AL 4.2 kg
6″ LACT6-500APL LACT6-500AL 4.4 kg
8″ LACT8-500APL LACT8-500AL 4.7 kg
12″ LACT12-500APL LACT12-500AL 5.3 kg
18″ LACT18-500APL LACT18-500AL 6 kg
24″ LACT24-500APL LACT24-500AL 7 kg
Industrial-Duty
(ID)
with ball
screw drive
450 kgf
[1000 lbs]
1.7 cm/s
[0.66″/s]
2.4 A –
13.2 A
4″ LACT4-1000BPL LACT4-1000BL 4.6 kg
6″ LACT6-1000BPL LACT6-1000BL 4.9 kg
8″ LACT8-1000BPL LACT8-1000BL 5.1 kg
12″ LACT12-1000BPL LACT12-1000BL 5.6 kg
18″ LACT18-1000BPL LACT18-1000BL 6.5 kg
24″ LACT24-1000BPL LACT24-1000BL 7.4 kg

Note that we are currently out of stock of many of the industrial-duty versions, but we will be getting more as Concentric makes them available. For units where the expected lead time is several months, we have disabled backorders; please contact us if you are interested in placing an order now for one of those units.

To see all of our linear actuators, visit our linear actuator category.

Bit-banding explained: A key feature of ARM Cortex-M3/M4

via Dangerous Prototypes

bit-band_Cortex-M3-Memory-map

Yahya Tawil over at Atadiat wrote in to let us know about a corner-stone feature in ARM Cortex-M3 processors called bit-banding:

Writing a portable code is one of the concerns for developers, and while dealing with bit-fields is not standard in all compilers, it is not very advisable to use.
When a feature is available in the hardware itself, you will not have any issues in porting the code from vendor to vendor while both are using the same ARM Cortex-M3 core.

ARM Cortex-M3 features a 1 MB area in SRAM memory called bit-band region. In this region each bit can be accessed individually. To access to bit-band region bits you need to do so via an aliased region, where each word in this region is an alias to one bit in the bit-band region.

More details at Atadiat homepage.

Via the contact form.

Free PCB coupon via Facebook to 2 random commenters

via Dangerous Prototypes

BP

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.