I was excited when the 555 contest was announced to recognize the most used Integrated Circuit ever.
After considering for a while what I could do for the competition, I started thinking about how best to celebrate the 40 years that the device has been around and the 10s of billions produced.
I have often admired home built computers that use discrete components so I though, I will make a 555!
This 555 project recreates an operational 555 timer using discrete transistors, resistors, diodes and capacitors.
It may not strictly conform to the competition rules, but I thought it would be fun and original anyway.
I downloaded a few 555 datasheets from various manufactures only to find that the circuits often have subtle differences. Eventually after some Googling I located a scanned copy of the original Signetics datasheet from dapj Circuits, Including the Equivalent Circuit below.
After inspecting the circuit, I noticed Q19 is rather unusual and has 2 collectors. How can I implement this using discrete components? I decided to simulate the circuit using the brilliant and free Java app from falstad.com to make sure it worked and to quickly experiment with different arrangements for Q19.
This is the simulation. You can run the simulation yourself by clicking the link .
Arranging the resistor on the base of Q19 as in the simulation works perfectly. If I used 2 transistors to replicate the original Q19 design, the circuit did not oscillate.
ConstructionIn order to simply construct the circuit to show its operation and at the same time preserve the original authenticity, I photocopied and enlarged the Philips schematic, glued it to some card and inserted the components through the card and used point to point wiring on the rear of the card.
Component side of card.
Rear of card using soldered point to point wiring. Drawing pins are used to secure the input and output pins. Much ice cream was consumed during the construction of this project.
A pin was used to poke holes in the card to insert the components. This was a surprisingly quick method of building the circuit. For prototypes of simple circuits I may use this technique again.
the only thing I might do differently is to paste a reverse image of the circuit onto the wiring side of the card in order to avoid wiring errors.
In order to test it works, I attached an LED to the output and suitable timing components, Ra, Rb and C to give an approximate 1Hz flash rate.
Making it presentable
The final thing to do is to make the project presentable. I decided the inside of an old data book would be appropriate. I found a copy of a suitable book on the ‘free’ table of my local ham radio club, the Manly Warringah Radio Society.
This was the first time I have used a book as an enclosure. It works well if you are not in a hurry, which I wasn’t. I followed the guide by Bre Pettis from Make Magazine. (Cool guy who I had the pleasure of meeting at a Maker Faire in Austin, Tx.)
One half of the book was cut to accommodate the circuit, while the other half was to house a battery, the 555 timer data sheet and memorabilia.
JOTA time already?? MWRS has hosted activities for the Scouts and Girl Guides for several years and this year was another busy and fun experience! We had around 180 kids come through the hall over the weekend of 19th-20th October. … Continue reading →
As the dust settled and the flags were packed away for next years activities I collected the logs, photos and evidence for review at a casual club meeting. Firstly I have to say for our first comp things went really well, we had contacts from across the land in conditions that were difficult to say the least.
By popular vote points for flags, setup and effort were awarded and the I am happy to announce that the winner is …… Geoff VK2MIA with 152 points.
Not only did Geoff have a flag pole station, he also had a pirate hat, pirate dreadlocks, a sea location, made SSTV contacts and emailed through photos that he had a random by passer take. If that wasn’t enough he also had to deal with someone telling him he couldn’t do “what ever it was he was doing”…
Special mention goes to VK3BQ for his awesome efforts in getting the word out in VK3 about our comp and his great sstv images. VK3YE and VK3BQ for the YouTube video and everyone else who participated in this fun event.
If you know of anyone missing please let me know asap..
The trophy was handed out on Wednesday night (Thanks Greg!) and now we look forward to next years INTERNATIONAL Flagpole Comp which will be held on Saturday 20th September 2014.
This is a fun and as you can see not too serious contest that will promote Amateur Radio and portable operations. So dust of your rig, get your antenna in the air and try out some new modes with friends.
Geoff (VK2MIA) procured a Flagpole for mobile operations and tweaked the interest of the wider club when he brought it up to the clubhouse one wednesday night. Upon inspection a group buy was in planning, with Shaun (VK2XPP) taking the lead. The club procured almost 2 dozen flagpoles (From here). Once shaun picked up the shipment the club members get right to business, with some great results.
So with all these flagpoles ready for field operations the idea for this contest was born and the point structure was decided upon around the club fireplace with more than a few laughs.
The winner of the competition will be the person who collects the most points during the day of the competition. The goal of the event is to exercise your ability to operate using a portable antenna across multiple modes and perhaps to get you out of your normal operating comfort zone.
Non-flagpole stations are welcome to participate, but will have to work a little harder to get points.
Rules are as follows
1. The Flagpole station must make up part of the antenna or antenna support.
2. The contest will run all day on the 21st of September 2013.
3. The President / Vice-President’s of the MWRS will be adjudicators.
4. This is a fun event, keep it fun and positive.
5. This event is open to all Amateur Frequencies and Modes.
6. A contact will be the exchange of Callsign, Signal Report and a quick report of your flagpole setup!
7. Log’s are to be submitted using the Competition spreadsheet. (See below)
Make a contact with a non-flagpole antenna 1 Point
Make a contact with a flagpole antenna 2 Points
Make a contact with another flagpole station 5 Points
Make a contact with D-Star 10 Points (Maximum of 100 Points)
Huge thanks goes to Mark and Chris for giving up their Saturday in the name of Amateur Radio. They have helped 5 new Amateur Radio operators get licensed, and held exams for 2 others to upgrade. Club member Lionel who … Continue reading →
Geoff Van der Wagen, Roger Hynes and Ben Menge. Photo courtesy of News Limited
This weekends International Lighthouse and Lightship weekend is a great opportunity to promote Amateur Radio, and with that in mind Club Publicity Officer Richard has done a great job working with the Manly Daily to get us some local press. A journalist from the publication visited the shack to meet with Roger, see first hand the restored Barrenjoey Radio and get some snaps of the guys in action.
I know everyone has their own favourite, but for me Lighthouse is the event of the year so keep an eye out for VK2MB / Lighthouse Portable on the airways!
To celebrate the big event MWRS is holding a BBQ this Sunday 21st April, from 3pm.
Anyone is free to attend but please email firstname.lastname@example.org to help us cater for attendees.
Come along and get introduced to Amateur Radio! We will have numerous members in attendance who will be more than happy to show you around our radio room, give you some tips on how to get started and share your enthusiasm for all things electronics, technology and radio.
This months lecture is by Carlo & Glen who show off the Mesh Potato project to club members. The Mesh Potato is a device for providing low-cost telephony and Internet in areas where alternative access either doesn’t exist or is too expensive. It is a marriage of a low-cost wireless access point capable of running a mesh networking protocol with an Analog Telephony Adapter.
This past weekend saw the annual John Moyle Field Day, which was contested by a few of our club members. Our resident contesting professor the honorable Patrick (VK2PN) was once again on the air with Horst VK2HL from the lovely Myall River on the NSW Mid North Coast.
For a full write up of his weekend I would suggest you hit up his blog.
Screen shot (stolen from the PocketPacket website)
I had a quick look at some iPhone APRS applications that used GSM connectivity to the Internet to publish my location, whilst those work very well when you have reception it isn’t as exciting as using RF to transmit your packets. Cue an Application called Pocket Packet.
Pocket Packet uses the iPhones built in GPS and a software-based TNC to encode 1200 baud packets, which are then outputted via the iPhones headphone jack your VHF radio.
I figure this is a great use for a old iPhone, which I happen to have. My old trusty iphone 3G had a hard life in the past, and after 2 years in the draw it is time to bring it back out. The great thing about using the iPhone as the TNC / GPS combo is it has its own battery built in (although I am yet to see how long it will last, I would guess 2 or 3 hours maybe. Coupled with a Baofeng UV-5R I snapped up off the Internet this is a cheap and simple tracker.
So to build up your own Iphone based APRS TNC / GPS unit follow my quick steps..
1. Install the App. Download it from the Apple AppStore (I should mention for Android people that I found an app called Aprsdroid which is a similar thing, I just don’t have an android to test it with). It would also be a good idea to read the user guide.
2. Make a radio <-> iPhone interface cable.
This is just a cable to go from your iPhones headphone jack to your radios Microphone jack.
I used a normal 2 pin 3.5mm headphone jack on both sides, here is my notes from when I made my cable.
Make sure you test your cable before you make everything tidy! Who knows maybe my notes are wrong!!
3. Start Pocket Packet, enter your callsign and slide down to the section labelled Audio Modem. Here you can enable the feature, and turn on the transmit function. Now this isn’t perfect right, it doesn’t seem to support smart beacons and you can’t set too many features but hey it’s cheap!
4. Enable VOX on your radio.
5. Bask in the awesomeness that is your new tracker.
Now seeing as I have a dedicated iPhone available for this I am working on making the application automatically start when the iPhone is turned on. This is not something that the iPhone supports natively so I am having to get under the covers. I also must note that VOX is a little hit and miss sometimes so you may need to spend some time testing what works best in your setup. I also put a RF Choke on my cable to minimise anything coming back from the radio to the phone.