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WE ASSUME CONTROL: SPI AND A DIGITAL POTENTIOMETER

In the last video I demonstrated a Universal Active Filter that I could adjust with a dual-gang potentiometer, here I replace the potentiometer with a processor controlled solid-state potentiometer. For those that are too young to remember, we used to say “solid-state” to differentiate between that and something that used vacuum tubes… mostly we meant you could drop it without it breakage.

The most common way to control the everyday peripheral chips available is through use of one of the common Serial Protocols such as I2C and SPI.  In the before-time back when we had only 8 bits and were lucky if 7 of them worked, we used to have to memory map a peripheral or Input/Output (I/O) controller which means we had to take many control and data lines from the microprocessor such as Data, Address, Read/Write, system clocks and several other signals just to write to a couple of control registers buried in a chip.

 

More at Hackaday.com

 

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MAKING THE CES SHOW… THIRTY YEARS AGO

This year’s CES has dredged up some memories. I had assumed that as one becomes old they are supposed to become used to memories of a young vigorous person that shared their body and memories leaving little else except some scars and some old stale socks lying around plus 2 or 3 pictures to prove it was in fact not a series of hallucinations. Turns out you don’t get used to it, you just endure.

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30 Years ago was our CES: Commodore had the reputation of showing something new every CES and this was a time when a Home Computer meant a Consumer Computer. I have written before about how we endeavored to make sure other’s failures didn’t become ours and we did in fact make it, just in time, to the ’85 CES with what became our flagship computer, at least for the next 4 days.

 

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WIRE WRAP 101

You might notice that many of my writings start with “Back in the day”. Not wanting to disappoint I will say that back in the day we used to use wire wrap technology when we needed a somewhat solid, somewhat reliably assembly. Given a readable schematic a good tech could return a working or near-working unit in a day or two depending on the completeness and accuracy of the schematic.

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Properly done a wire wrap assembly is capable of fairly high speed and acceptable noise when the alternative option of creating a custom PCB would take too long or not allow enough experimentation.  Wire wrap is also used in several types of production, from telco to NASA, but I am all about the engineer’s point of view on this.

My first wire wrap tool and wire wrap wire came from Radio Shack in the mid 1970’s.  I still have the wire, because frankly its kind of cheap wire and I use it when it’s the only thing I can reach quickly when I need to make a jumper on a PCB. The tool is still around also, given the fact that I can’t find it at the moment the one shown here is my new wire wrap tool which is good for low quantity wrapping, unwrapping and stripping.

Read more at Hackaday.com

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Join me at VCF East Friday April 17th

I will be doing a workshop this Friday at VCF East on computer architecture. Each year is bigger and better and this is the second year for three days of computer related festivities. Worth the drive if you are in the NJ, NY, PA area!

http://www.vintage.org/2015/east/session.php

 

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Thermocouple Amplifiers

I just did a video for Hackaday about Thermocouple Amplifiers, a quickie video feature Linear Technology in this case.  The spares from the build for the video are available at http://www.herdware.com/shop/analog/thermocouple-amplifier/ along with a Type K Thermocouple.

From the Hackaday video

Thermocouple is a terrific way to measure temperature. The effects of temperature change on dissimilar metals produces a measurable voltage. But to make that measurement you need an amplifier circuit designed for the thermocouple being used.

Linear Technology LTC 1049 Low Power Zero-Drift Operational Amplifier with Internal Capacitors

Linear Technology LTC 1049 Low Power Zero-Drift Operational Amplifier
with Internal Capacitors

While researching “Zero Drift Amplifiers” as a follow-up to my video on Instrumentation Amplifiers I noticed the little schematic the front page of theLTC1049 datasheet which is shown here. I thought it was an ideal example of an analog application where some gain and some “gain helper” were needed to accomplish our useful little application of amplifying a thermocouple probe.

Read More at Hackaday

 

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No Audio Preview in Pinnacle Studio

Evidently when more than one capture card is present in a system, say for example you have AV capture cards, you need to add an ASIOIO directive to the settings.ini file for Pinnacle.

You would not find the file yourself unless you work for MS. C:\Users\Public\Documents\Pinnacle\Program Files(x86)\Pinnacle\Studio 15\programs\Sites\[ComputerName]\Settings

To force DirectSound playback, add the following key in the file “settings.ini”.

[ASIOIO]
SEL_DEVICE_SZ=00000000-0000-0000-00-00-00-00-00-00-00-00

Sadley I couldnt find the KB by searching, probably just my inability to type and not a strange search index at Avid . http://avid.custkb.com/avid/app/selfservice/search.jsp?DocId=214049

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How to Install Cisco VPN Client on Windows 7

This appears to be typical of what is needed to get Windows 7 to live with Cisco VPN client:
http://weblogs.asp.net/bhouse/archive/2009/01/15/how-to-successfully-install-cisco-vpn-client-on-windows-7.aspx

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