Common TTL and CMOS Logic Gates

November 26, 2018

I been using a lot of TTL and CMOS logic gates in my recent RC2014 circuits and after realising that I had loaned out my much used copies of TI’s TTL Logic data books some time again and never got them back so to help me I created this quick comparison table for the common TTL and CMOS logic gates.

For completeness here’s a logic truth table:

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eDay7

October 31, 2018

We were at eDay again earlier in the month (Saturday 6th October 2018) as part of Newcastle Maker Space. This is the seventh year its been going and as usually we had a great time showing off various projects.

We had the following R-Kade and PiZythn and Rc2014 projects on show.

For those who don’t know what eDay is: eDay is a local digital skills day where various digital technologies are demonstrated to an enquiring general public. A sort-of geeky show and tell where local groups and individuals meet at Gateshead Central Library and show off their projects or what interests them.


No more Maker Faire UK

October 3, 2018

It was with great sadness that I read that Maker Faire UK will not be coming back next year.

The venue Centre for Life in Newcastle has hosted the maker event since 2009 and was the very first venue to host a Maker Faire outside of the United States.

I’ve been a regular visitor and exhibitor since 2010 and enjoyed every moment of my time at it.

Fortunately, there are still plenty of other Mini Maker Faire’s in the UK and I’ll hopefully be visiting some of them next year instead.

 

So a final thank you to Maker Faire UK, to the people who organised it, to the exhibitors who showed off many great projects and to the many visitors who came to see what it was all about.

 

Here’s the message from Maker Faire UK web site:

Important news

In 2009, Life Science Centre brought Maker Faire to the UK and has hosted the country’s flagship event ever since. Over that time, the popularity of making activities in the UK has sky-rocketed.

Life is proud to have been pioneers in this growing Maker movement, but we feel the time is right to make a change and to bid a fond farewell to Maker Faire UK. Lovers of all things making needn’t fear, as we’re opening a new space in Life Science Centre dedicated to crafting, tinkering and creativity in the spring of 2019.


Raspberry Pi Hardware GPIO Shutdown

September 12, 2018

I found this snippet of knowledge from the Raspberry Pi forum the other day when searching for a easy way to shutdown a RPi from a simple push button.

Open /boot/config.txt in your favorite Raspbian editor and add the following line:

dtoverlay=gpio-shutdown,gpio_pin=7

You may need to add a pull-up resistor to the GPIO pin or add the instruction gpio_pull=up to the instruction. You can also leave out the gpio_pin and the system will default to GPIO3.

You can also monitor the RPi’s status by adding this line to config.txt:

dtoverlay=gpio-poweroff,gpiopin=27,active_low=1

GPIO27 will be high to indicate when the RPI is running or low when it is shut down.

There is more detailed information here:
https://www.raspberrypi.org/forums/viewtopic.php?t=221997
https://github.com/raspberrypi/firmware/blob/master/boot/overlays/README


8052 CPU card for RC2014 Bus

August 31, 2018

A few months ago I mentioned a 8031/8052 CPU card I had designed for the RC2014 bus. Here’s a couple of pictures for an assembled card. I’m just starting to test it out so I will post results shortly.


Old tech books = fun

July 31, 2018

When design and building my recent RC2014 boards one of the things I’ve found most useful and fun to re-read them after so many years has been my collection of great old tech books and data books. You’ll probably recognise a few of them. Here’s a brief list in no particular order:

 

 

 


Apple II Prototyping PCB’s

June 29, 2018

I recently came into possession of a Apple IIe (an enhanced Apple II from the early 80’s) and decided to build a few PCB’s to help get this old warhorse back up in running. The first board  designed was an extender card for the Apples expansion card to make testing and fault finding them a little easier. The second PCB was a prototyping board to allow me to build up various test circuits.

 

Both will be available on Tindie soon