Oh What A Busy Few Days
Wednesday started with a meeting with my Masters project supervisor. All went OK, but I'm still finding it hard to get properly motivated. Rest of the day spent following up on that and preparing for the Dorkbot Hack Day. The theme is "mobile music", and that leads to Arduinos running music-generating code. Also a trip to the UWE library in search of circuits.
The main thing to do on Thursday was to get the Farnell order sent off. I got a selection of stuff for Dorkbot, as well as some TL071 op-amps for the microphone preamp. That was done by 2pm, easily in time for the parts to arrive the next day. Thursday evening was a pre-Hack Day meeting for Dorkbot Bristol, at the Watershed. I took the City-El electric bubblecar, did a few errands and purchased some parts from Maplin. Also got some balsa wood (3/8 inch thickness) for use with drawing pins for circuit-building!
Friday morning and sure enough, the parts arrived. All good and ready to go for Sunday. Trip to Cabot Circus in the evening for sushi with friends. Discovered last thing in the evening that I'd ordered programmable unijunction transistors (2N6027, 20p each) instead of unijunction transistors (2N2646, £2.50). So that'll mean a slight change to the circuit to get them working as oscillators.
Saturday was the occasion of aminorjourney and k81ng's civil partnership. Friends and family arrived from far and wide. I was acting as photographer for the day, too. All went very well, the weather was sunny and the day ended with everyone tired but happy.
Sunday was Dorkbot Bristol Hack Day. I hadn't really left myself enough time to pack up the stuff I needed to take, which meant a last-minute rush and a few things left behind (nothing vital). The trip down to Stokes Croft, with the car fairly heavily loaded, gave me doubts about making the return trip without charging. So, to be on the safe side, I ran over to Cabot Circus again for the charging bays. In fact, I'm wondering if the trouble is actually poor instrumentation in the car rather than actually using up the batteries after less than seven miles (they were at 36.6V before charging).
As for the Hack Day, we had circuit-benders working on the spoils of a trip to the Bradley Stoke car boot sale, we had simple oscillator circuits made on balsa wood and drawing pins, we had an Arduino tapping out rhythms on a bank of solenoids and we had my project, an Arduino generating music based on trigger pulses from an optical sensor. I wired up the sensor initially to an LED, which revealed that it needed patches of light and dark surfaces about 25mm in size. Shiny metal bulldog clips also worked, but had to be accurately aligned with the sensor. We decided to use black felt pen on white paper, and keep the blobs over 25mm. Ultimately, the sensor will be attached to a dismembered bicycle.
Meanwhile, the Hamilton House lift had failed. It was forlornly trying to close its doors, but sensing a ghostly obstruction every time. We had to stage an escape via a roundabout route that brought us out at the Gloucester Road side of the building, instead of coming out at the car park side on City Road. Getting back in was more convoluted, requiring someone on the inside to open one of the inner doors for us. Suggestions were made that a tunnel could be dug, avoiding the razor wire and by-passing the searchlights and guard towers (for the full effect, imagine somebody whistling the theme from The Great Escape).
Back at the Arduino, I took the existing delay-based code and made it respond to the logic state on Digital Pin 2. Now, we got a new note whenever the sensor was triggered. A swiftly applied paper disc on the bicycle wheel was followed by some equally swiftly applied gaffer tape to fix the sensor onto the bicycle forks.
Finally, we had a working Arduino program and a working opto-sensor, set up on the bicycle wheel with an amplifier and a battery. You could spin the wheel and get the Arduino to play a new note each time the dark spots passed underneath the sensor. Success!
After another Great Escape back to the car park, this time with three other escapees carrying the tech gear, I loaded up the bubblecar and made a silent exit. The trip back seemed to go better, leaving me with 37.2V on the batteries. I made a minor repair to the sunroof by replacing a bolt that had fallen out the day before.
The main thing to do on Thursday was to get the Farnell order sent off. I got a selection of stuff for Dorkbot, as well as some TL071 op-amps for the microphone preamp. That was done by 2pm, easily in time for the parts to arrive the next day. Thursday evening was a pre-Hack Day meeting for Dorkbot Bristol, at the Watershed. I took the City-El electric bubblecar, did a few errands and purchased some parts from Maplin. Also got some balsa wood (3/8 inch thickness) for use with drawing pins for circuit-building!
Friday morning and sure enough, the parts arrived. All good and ready to go for Sunday. Trip to Cabot Circus in the evening for sushi with friends. Discovered last thing in the evening that I'd ordered programmable unijunction transistors (2N6027, 20p each) instead of unijunction transistors (2N2646, £2.50). So that'll mean a slight change to the circuit to get them working as oscillators.
Saturday was the occasion of aminorjourney and k81ng's civil partnership. Friends and family arrived from far and wide. I was acting as photographer for the day, too. All went very well, the weather was sunny and the day ended with everyone tired but happy.
Sunday was Dorkbot Bristol Hack Day. I hadn't really left myself enough time to pack up the stuff I needed to take, which meant a last-minute rush and a few things left behind (nothing vital). The trip down to Stokes Croft, with the car fairly heavily loaded, gave me doubts about making the return trip without charging. So, to be on the safe side, I ran over to Cabot Circus again for the charging bays. In fact, I'm wondering if the trouble is actually poor instrumentation in the car rather than actually using up the batteries after less than seven miles (they were at 36.6V before charging).
As for the Hack Day, we had circuit-benders working on the spoils of a trip to the Bradley Stoke car boot sale, we had simple oscillator circuits made on balsa wood and drawing pins, we had an Arduino tapping out rhythms on a bank of solenoids and we had my project, an Arduino generating music based on trigger pulses from an optical sensor. I wired up the sensor initially to an LED, which revealed that it needed patches of light and dark surfaces about 25mm in size. Shiny metal bulldog clips also worked, but had to be accurately aligned with the sensor. We decided to use black felt pen on white paper, and keep the blobs over 25mm. Ultimately, the sensor will be attached to a dismembered bicycle.
Meanwhile, the Hamilton House lift had failed. It was forlornly trying to close its doors, but sensing a ghostly obstruction every time. We had to stage an escape via a roundabout route that brought us out at the Gloucester Road side of the building, instead of coming out at the car park side on City Road. Getting back in was more convoluted, requiring someone on the inside to open one of the inner doors for us. Suggestions were made that a tunnel could be dug, avoiding the razor wire and by-passing the searchlights and guard towers (for the full effect, imagine somebody whistling the theme from The Great Escape).
Back at the Arduino, I took the existing delay-based code and made it respond to the logic state on Digital Pin 2. Now, we got a new note whenever the sensor was triggered. A swiftly applied paper disc on the bicycle wheel was followed by some equally swiftly applied gaffer tape to fix the sensor onto the bicycle forks.
Finally, we had a working Arduino program and a working opto-sensor, set up on the bicycle wheel with an amplifier and a battery. You could spin the wheel and get the Arduino to play a new note each time the dark spots passed underneath the sensor. Success!
After another Great Escape back to the car park, this time with three other escapees carrying the tech gear, I loaded up the bubblecar and made a silent exit. The trip back seemed to go better, leaving me with 37.2V on the batteries. I made a minor repair to the sunroof by replacing a bolt that had fallen out the day before.