For Fun
RealTimer for RealTalk
ReelTalk is a combination AM/FM radio and tape recorder. The tape recorder operates at 1/4 speed, which means that you can record up to 220 minutes on one side of a 110 minute cassette. If the program you wish to record is longer than 220 minutes, you've got a problem. For example, Art Bell's 5 hour radio show doesn't fit on one side of a cassette (RealTalk doesn't have an auto reverse feature).
Enter RealTimer! RealTimer is a software application that turns AC power on and off by using the computer's parallel printer port. RealTimer can be programmed to turn the ReelTalk radio and tape off during station breaks at the top and bottom of the hour and back on when the radio show resumes! Art Bell's 5 hour show now fits on less than one side of a 110 minute cassette.
This web page provides the source code and executable for RealTimer and explains how to build the necessary hardware. A word of CAUTION is warranted. This project involves working with hazardous voltages. It is possible that such voltages could kill you. If you don't have basic electronic skills, find someone to construct this project for you. I cannot take responsibility for what you do; only you are responsible for what you do. So again, take care when building this project or find a friend who has the proper skill set.
     Click on the following picture to see a sample system. The Zeit radio controlled clock monitors WWV and insures the laptop's system clock operates with split second accuracy. WWV is a radio station operated in Colorado, which serves as a time and frequency standard with the accuracy of an atomic clock.
The Zeit clock keeps the laptop running on time. RealTimer software running on the laptop outputs a signal to the parallel printer port that controls three of the power strip's 6 AC sockets. RealTimer follows timing instructions in a data file that tell it when to turn the AC power on and off.
The antique radio in the background is a Montgomery Ward Airline radio that receives the standard AM band through the 16 meter band.
     Here is a picture of a modified power strip. Click on the picture to get a better view. Note the stereo mini-phone jack and neon light on the left-hand side of the power strip.
     An opto-isolated triac is used to control the three AC power outlets. Click on the following picture to see the packaged opto-isolated triac.
     The computer's printer port is used to drive the LED inside of the device. The eight printer data output lines are connected in parallel through current limiting resistors to drive the LED. Click on the following picture to see a better view of the DB-25 parallel port connector with the eight resistors soldered in place.
     The three AC outlets that will be controlled by the opto-isolated triac must be isolated from the other three AC outlets. Usually three brass strips are used to make the hot, neutral and ground connections with plugs inserted into the six AC outlets. The 'hot' brass strip that carries power to the last three AC outlets must be cut so the opto-isolated triac can be soldered in. To help identify the 'hot' brass strip, look on the front of the power strip. There are two cutouts per AC outlet where the two flat 'blades' of the plug are inserted. Note that one of the blade cutouts is shorter than the other. The shorter blade of the two is where the 'hot' connection is made. The neutral connection is made with the longer blade. Click on the following picture for a larger view of the front of the power strip I modified.
     Turn the power strip over and cut the 'hot' bus (remember: the short blade). Bend the edges of the brass bus so the leads from the opto-isolated triac can be soldered to the bus making both a good mechanical and electrical connection. Click on the following picture to see a better view of the opto-isolated triac I soldered into my power strip. In the picture the diagonal cutters are positioned to demonstrate how I cut the bus.
Look at the opto-isolated triac and identify which leads are soldered to the 'hot' bus, and which will go to the mini-jack. On the opto-isolated triac that I used, the leads that will be soldered to the 'hot' bus (AC load) had a tilde ('~') between them. The tilde represents alternating current (AC). The two other leads, which go to the LED, were identified with a plus ('+') and a minus ('-') sign.
     Click on the following picture for a close up of an opto-isolated triac as it comes out of the package next to an installed opto-isolated triac.
When positioning the opto-isolated triac in the power strip, make sure to bend the LED ('+' and '-') leads so that there is no way they could ever come in contact with any of the brass busses. Before doing any soldering, make sure that all four leads are bent so that the opto-isolated triac will properly fit in the power strip.
Solder a red wire (or other suitable color) to the LED '+' lead and a black wire to the LED '-' lead. Allow enough wire to reach the location of the mini-jack.
You will need to drill two holes in the power strip in order to install the neon light and stereo mini-jack. Locate the neon light so that its two wires can easily be soldered to the neutral and hot busses. Locate the stereo mini-jack so that after the black and red LED wires are soldered on, there is no way any hazardous voltages can come into contact with them.
After the neon light and mini-jack have been installed, prepare to solder the opto-isolated triac into place. Route the LED wires so they are out of the way of all busses and plug openings. The wires should lay neatly along the side of the power strip. Insure that the wires will not be trapped or squeezed when the power strip base is reinstalled.
Before soldering the opto-isolated triac into place, you may wish to fold the brass bus over the triac leads to make a solid mechanical connection. Now solder the opto-isolated triac leads to both side of the 'hot' bus.
Now solder the LED wires to the stereo mini-jack. The stereo mini-jack has three connections called tip, ring and ground. The tip contact is the connection that makes contact with the very tip of a stereo plug. The ring is the connection which is between the tip and ground connections. We will be connecting the red LED wire to the tip contact and the black LED wire to the ring contact. The ground contact will not be used.
Now solder the two wires from the neon light to the 'hot' and 'neutral' busses. Don't solder either wire to the round bus.
     Click on the following picture to see a bigger view of my completed power strip. Note the yellow disk on on the right side of the power strip between the switch and the circuit breaker.
The yellow disk that you saw in the picture above is a metal oxide varistor (MOV). This is the device that suppresses power line surges. On my power strip, the MOV was located on the left side of the power strip where the neon light and mini-jack are now located. I moved it to its present location so I'd have room for the neon light and mini-jack, but more importantly I moved it so that it would not be switched 'in' and 'out' of the circuit by the opto-isolated triac. Had I left the MOV in its original position, power surges would have traveled through the opto-isolated triac--bad idea.
Reassemble the power strip. Test that three of the outlets provide power to your radio and the other three don't. With nothing connected to the three switched outlets, you may notice a very dimly lit neon light--this is normal. A neon light takes so little power that leakage current through the opto-isolated triac may cause it to be dimly lit or flicker.
The final step is to make a cable to connect the power strip to a computer's parallel port.
Add RealTimer software to control the outlet, and voila! Ready to go!
Here is the source, executable and sample schedule file (RealTimr.zip -- 28 kBytes). This program was extensively used under Windows 95. It should work fine under any Windows 9x but it will not work under Windows NT as it issues IO writes directly to the parallel port. This program has been successfully modified to run under FreeBSD.
Quiet Designs Inc.    Grass Valley, California, U.S.A.    (555) 555-1212    E-mail: webdude@example.com