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Re: Buying an Oscilloscope

 by mac ¦  Mon Jun 14, 2010 3:55 am ¦  Forum: Wireless/RF ¦  Topic: Buying an Oscilloscope ¦  Replies: 22 ¦  Views: 12329

13.56 x 2 Msamples/s is the absolute minimum you need to reconstruct the signal with a sin(x)/x approximation. In reality you need at least four times, up to 10 times the shannon limit. Why? because mostly you seek for non-linearities or higher band harmonics. And yes 32k (in fact 14k for DSO from h...

Re: Soldering Station comparison?

 by mac ¦  Thu Jun 10, 2010 2:42 am ¦  Forum: SparkFun Product Questions ¦  Topic: Soldering Station comparison? ¦  Replies: 10 ¦  Views: 3800

Hi, I don't think it's an issue with "cloning", as most chinese products are rebranded and resold under myriad of names (it's a CSI one btw). It comes from the design of the tip itself: it slides on the ceramic heating element. If not well sitted or dirty (from oxydation) contact can be suboptimal. ...

Re: Linux — What should I use to program and/or debug?

 by mac ¦  Wed Jun 09, 2010 4:10 am ¦  Forum: AVR Microcontrollers ¦  Topic: Linux — What should I use to program and/or debug? ¦  Replies: 5 ¦  Views: 1395

"Bare metal" development tools on my side: Cross gcc generated by crossdev tool (gentoo). You can do it by hand but it's tricky (bootstrap gcc + libc build). Emacs for editor (not for dummies, or for dummies with motivation), with additions like global for tags. OpenOCD (arm)/avarice (avr) + gdb + d...

Re: Soldering Station comparison?

 by mac ¦  Wed Jun 09, 2010 12:25 am ¦  Forum: SparkFun Product Questions ¦  Topic: Soldering Station comparison? ¦  Replies: 10 ¦  Views: 3800

Hi, I first purchase a clone of the hakko 937, quickly changed for a clone of aoyue 2901 (the analog version). The 937 is not a bad station, but is clearly behind the 290x serie: less power, not so good contact between tip and heating element. If you do only pb solder, 937 is ok, if you do lead free...

Re: Maxim AN438 breakout board

 by mac ¦  Thu Jun 03, 2010 6:03 am ¦  Forum: New Product Ideas ¦  Topic: Maxim AN438 breakout board ¦  Replies: 1 ¦  Views: 435

LTC3785 is also a good candidate: buck/boost topology, but it requires external mosfets (3) and is a QFN package.

Re: Digital or analog iron?

 by mac ¦  Wed Jun 02, 2010 4:42 am ¦  Forum: SparkFun Product Questions ¦  Topic: Digital or analog iron? ¦  Replies: 4 ¦  Views: 751

I had a CSI 2A station, quite good but not enough power for leadfree solder.
Switched to a CSI-2901, analog one, quite more power and very good for leadfree.

Analog or digital is more a matter of taste, under the hood it's the same control system.

Maxim AN438 breakout board

 by mac ¦  Thu May 27, 2010 4:29 am ¦  Forum: New Product Ideas ¦  Topic: Maxim AN438 breakout board ¦  Replies: 1 ¦  Views: 435

I was searching for a cheap and quite efficient way to power 3.3v circuit from a li-ion battery.

I found Maxim AN438 which is very interesting.

I think it can be a good start for a 3.3v li-ion psu breakout and a good addition to li-ion charger breakout. Maybe adding a auto-shutdown circuit also.

Re: high torque motor for solar tracker

 by mac ¦  Fri May 21, 2010 12:33 am ¦  Forum: SparkFun Product Questions ¦  Topic: high torque motor for solar tracker ¦  Replies: 10 ¦  Views: 1830

500 Nm? Are you sure? What speed?

For 18rpm, it means 2Hp motor reducter. And output gears need to be in the industrial ballpark, no toys allowed!

Re: plasma module

 by mac ¦  Fri May 07, 2010 12:46 am ¦  Forum: New Product Ideas ¦  Topic: plasma module ¦  Replies: 20 ¦  Views: 2886

are there any straight handled handheld plasma cutters? seems all i can find around has a bent handle that does not make it cosy to embed the thing. But if you seriously want to make a arduino controlled plasma cutter for 4mm Al. then you want to look at a handheld plasma cutter and adapt it to mov...

Re: Why do SD card FAT16 files >100MB become corrupt

 by mac ¦  Wed Apr 21, 2010 7:27 am ¦  Forum: SparkFun Product Questions ¦  Topic: Why do SD card FAT16 files >100MB become corrupt ¦  Replies: 25 ¦  Views: 3294

markaren1 wrote:Using a PC and card adaptor write a large file to each card, time transfers.

See if there is any obvious difference between card performance.

Not relevant as SD card reader do not use SPI mode for reading/writing.

Re: plasma module

 by mac ¦  Thu Apr 15, 2010 7:53 am ¦  Forum: New Product Ideas ¦  Topic: plasma module ¦  Replies: 20 ¦  Views: 2886

Small module for cutting 4mm alu?

You need to be in the 30-40A ballpark to do this. This mean at least full power from an 220v/16A outlet...

And beware most cheap chinese plasma cannot be used nearby electronic due to HF arc starting method.

Re: circuit design of 4-wire bipolar motor COILS

 by mac ¦  Wed Apr 14, 2010 9:22 am ¦  Forum: SparkFun Product Questions ¦  Topic: circuit design of 4-wire bipolar motor COILS ¦  Replies: 3 ¦  Views: 468


It's a bad idea to dismantle hybrid stepper motors.
You have a great chance to loose most of its torque due to demagnetization of the rotor.

This usually happens when rotor poles touch stator. I know because I killed one like this...

 by mac ¦  Thu Feb 18, 2010 4:01 am ¦  Forum: Everything ARM and LPC ¦  Topic: STM32F103 Where to begin... ¦  Replies: 6 ¦  Views: 9146

On windows there is various toolchain precompiled, I will not comment on them. On Linux, since I use gentoo I have access to the wonderfull crossdev tools, which allows to compile toolchain quite smoothly. Otherwise you need to learn how to compile your toolchain. Not difficult but tedious. I use jt...

 by mac ¦  Wed Feb 10, 2010 5:28 am ¦  Forum: Code ¦  Topic: Arduino + rotary encoder ¦  Replies: 8 ¦  Views: 40191

You should debounce the input if encoder is mecanical and not optical. Even with high quality mecanical ones there could be some bouncing. If they are bouncing it's most of the time short bursts of pulses which can be very annoying if you work with interrupts. The idea with debounce is to double che...

 by mac ¦  Fri Jan 29, 2010 2:34 am ¦  Forum: SparkFun Product Questions ¦  Topic: How to choose a soldering iron? ¦  Replies: 12 ¦  Views: 3448

In uk you have Allendale or CircuitSpecialist europe , so you can have some low-cost chinese stations. I have one, and they are quite ok for hobby use. Both are serious vendors (I have a CSI station 2A and is a regular customer of allendale). As you will use leadfree solder, be sure to get a powerfu...