This page is dedicated to projects that are currently underway in the Lab. At any point in time, I usually have several projects that I'm working on and they can be in just about any state of completion. Check back from time to time and see what's new.
New Prototype Board
I just received one of the new Parallax Electronics <http://www.parallax.com> Professional Development Boards. While designed for the Basic Stamp, Javelin Stamp and Ubicom SX28 series of microcontrollers, and a bit pricey at $149, it provides a great platform for Microchip PIC development. All of the peripherals are available through on board headers, and there are a lot of peripherals.
The list includes:
 | 5 volt, 1.0 amp power-supply with power switch |
| 16 discrete blue LEDs |
| Five blue 7-segment (with decimal point), common-cathode LED displays |
| Parallel LCD (available separately) may be configured in 4-bit or 8-bit mode |
| Two servo-compatible headers |
| Two 10k Ohm potentiometers |
| Audio amplifier with built-in speaker; with switch for external speaker |
| L293D high-current driver for motors, solenoids, etc. |
| Eight, normally-open pushbuttons (I/O lines protected, and pulled-up to Vdd via 10K) |
| Eight DIP switches (I/O lines protected, and pulled-up to Vdd via 10K) |
| Pulse generator with selectable frequency (1 Hz, 10 Hz, 100 Hz, or 1 kHz) |
| RJ-11 connector; configurable for X-10 and 1-Wire® communications |
| RS-232 DCE port with MAX232E transceiver |
| DS1307 (I2C®) real-time-clock with 3v back-up battery (pre-installed) |
Parallax provides complete documentation, including a schematic, on their web site. <http://www.parallax.com/detail.asp?product_id=28138>
Update (7/11/2005) - While I love the prototype board, I have major reservations about the recommended 12 Volt 1A power supply that Parallax sells. (Stock#: 750-00007) Measuring 16+ Volts open circuit it definitely isn't a regulated supply. Since I'm not using the development board with a Stamp processor, I'm not loading the power supply enough and as a result, I'm seeing 15 Volts supplied to the LM386-1 audio amplifier. The chip is rated at 15 Volts maximum and I'm a bit uncomfortable pushing the limits. For now, I'm going to either use a gel cell battery or the regulated lab supply on my bench. Updates to follow.
LCD Pin Out Issues
One of the first things I did with the prototype board was to build out a cable to connect an external character based LCD display to the board. I have a stock of displays made by Lumex that I bought from Mouser. In particular, the LCM-S01602DSF/C 16x2 displays. This particular display uses Pin 1 as VDD (+5V) and Pin 2 as VSS. (Ground). Just about every other display including Optrex, and Hantronix have Pin 1 as Ground and Pin 2 as the supply voltage. The prototype board is designed using the standard LCD pin out. As a result, a cross over of Pins 1 and 2 is required at one end of the cable.
PIC Based Keyer Build Out
I've started building out several Microchip PIC based keyers to run timing tests on. One of the first to be built is the K1EL K8 keyer which is based on a 12F509 microcontroller. (The design originally used a 12C509 OTP chip, but the 12F509 is a drop-in replacement that offers re-programmable FLASH program memory.) The photo below shows the keyer chip on the prototype board.
Sealed Lead Acid Battery Upgrade
I've had two, 24 AH YUASA Gel Cell batteries in the shack that I've used for backup power for years. After purchasing a West Mountain Radio Computerized Battery Analyzer - CBA II <http://www.westmountainradio.com/CBA_ham.htm> at Ham-Com this June, I finally decided that the old Gel Cells had to go. At best they had 80% of their rated capacity. At worst, they could fail just about anytime.
So it was time for a new battery. What I wound up with was a 99 AH marine deep cycle battery (MK27AGM) from Minn Kota (Trojan) courtesy of the new Cabellas down the road. It's a group 27 battery and weighs 66 pounds!
Now that the battery and a battery box were in place, it was time to charge the battery. Unfortunately, my little Jade Electronics 1A smart charger isn't going to be up to the task.
I ordered an A&A 5 Amp Smart Charger. It arrived and it works great. I purchased it to use in the shack when I need to keep the RFI down. Most of the bigger chargers, including the Xantrex, use a switchmode power supply which can cause RFI in the shack.
I really like the IOTA DLS chargers with the IQ4 Smart Charge Controller (and they are built in the U.S.) but the smallest one they make is a 15 Amp which would be a C/6 charge rate. C/6 is a much faster charge that I'd normally like to see with a sealed battery. Usually, I shoot for a C/8 to C/10 charge rate. Also, the IOTA's voltages are targeted for a flooded battery and not a VRLA (Gel or AGM) battery. IOTA's web site is at <http://www.iotaengineering.com/dls.htm>
APRS
I've just gotten involved in APRS, primarily as a result of purchasing a Kenwood TM-D700A transceiver for myself. If you are not familiar with the D700A, it is a dual band VHF/UHF transceiver with a built-in 1200 and 9600 bps TNC and GPS interface. It will even display APRS information from other stations without a terminal. The D700 also works great receiving telemetry and PBBS data at 9600 bps from the AO-51 satellite.
So far, I've only operated from my home but if you are interested, try visiting: http://www.findu.com/cgi-bin/find.cgi?call=ka0iqt-3 and see if I'm mobile or at the new QTH.
Since I like playing with PIC microcontrollers, I'm building a little TNC using a PIC and a MX614 modem chip. I'm using the MIC-E from TAPR as a baseline design and working from there. I'm going to add an RS-232 interface and include some additional capability including some 1-wire sensors. I'll be testing the TNC using an old Icom IC-207H transceiver. Details to follow.