Hello, this is my first post here so I guess I'll introduce myself. My name is Matt and I'm an electrical engineering student, currently a sophomore. I recently got an Amateur radio operator's license which is where this project got its start. I'm an EE major but it will surprise you how little I know about circuits thus far. Anyway...
I'm putting together a morse code keyer, for those who don't know what that is, it is a device that a morse code key is connected to that creates a tone so you can hear what you are sending. It also puts the transceiver into transmit mode. It has a few more functions but that's basically what it does.
I am pretty much a noob when it comes to circuits, I mean I know how to solder and I've put together a few altoids can guitar amps and even wired a strat. My project will be a combination of 2 kits available on the web as well as an LM386 amp. The first kit is the actual keyer, the second kit is a capacitive touch circuit that will be used as the morse key to input into the keyer.
Kit 1: http://www.hamgadgets.com/store/product_info.php?products_id=89
Kit 2: http://www.cwtouchkeyer.com/P3W.htm
LM386 circuit: http://web.mit.edu/6.s28/www/schematics/lm386.htm
The Picokeyer uses 2.5 -5.5V and draws a max 2mA, and the touch key uses 6 - 14V and not sure about current draw. I'm planning to use a 9V 1A wall wart to power the touch key and the LM386 and then using a voltage regulator like the 78L05 but with a 3V output to power the picokeyer. The speaker connected to the LM386 will be an 8Ω ripped from an old pc speaker set. I have no idea if a 9V 1A supply is enough or ideal for this project so I would appreciate any opinions.
I'm using the lm386 because I'm going to put this into a plastic case and the piezo transducer the picokeyer uses will be too quiet to hear. The tone output from the picokeyer is a square wave. The kit maker says that if you integrate the kit with homebrew equipment that you should use a low pass filter to make it cleaner. (I believe Morse code tones can range from about 250-900Hz) Now I was wondering if the filter should go on the input of the LM386 or the output to the speaker. Also, would some sort of square-to-sine wave filter be better than an lp filter? I don't know what would go into converting a square wave to a sine wave but an lp filter would probably only have a small cap and coil right?
One more thing, sorry this is so long! I want to use a 100k pot to control the volume but should the pot go before or after the amp?
I will post updates and pictures throughout the project if anyone is interested, maybe even a video. Here's a quick video I found of the picokeyer: http://www.youtube.com/watch?v=660WwT63I_Q
Thanks in advance,
Matt KC9QNC
I'm putting together a morse code keyer, for those who don't know what that is, it is a device that a morse code key is connected to that creates a tone so you can hear what you are sending. It also puts the transceiver into transmit mode. It has a few more functions but that's basically what it does.
I am pretty much a noob when it comes to circuits, I mean I know how to solder and I've put together a few altoids can guitar amps and even wired a strat. My project will be a combination of 2 kits available on the web as well as an LM386 amp. The first kit is the actual keyer, the second kit is a capacitive touch circuit that will be used as the morse key to input into the keyer.
Kit 1: http://www.hamgadgets.com/store/product_info.php?products_id=89
Kit 2: http://www.cwtouchkeyer.com/P3W.htm
LM386 circuit: http://web.mit.edu/6.s28/www/schematics/lm386.htm
The Picokeyer uses 2.5 -5.5V and draws a max 2mA, and the touch key uses 6 - 14V and not sure about current draw. I'm planning to use a 9V 1A wall wart to power the touch key and the LM386 and then using a voltage regulator like the 78L05 but with a 3V output to power the picokeyer. The speaker connected to the LM386 will be an 8Ω ripped from an old pc speaker set. I have no idea if a 9V 1A supply is enough or ideal for this project so I would appreciate any opinions.
I'm using the lm386 because I'm going to put this into a plastic case and the piezo transducer the picokeyer uses will be too quiet to hear. The tone output from the picokeyer is a square wave. The kit maker says that if you integrate the kit with homebrew equipment that you should use a low pass filter to make it cleaner. (I believe Morse code tones can range from about 250-900Hz) Now I was wondering if the filter should go on the input of the LM386 or the output to the speaker. Also, would some sort of square-to-sine wave filter be better than an lp filter? I don't know what would go into converting a square wave to a sine wave but an lp filter would probably only have a small cap and coil right?
One more thing, sorry this is so long! I want to use a 100k pot to control the volume but should the pot go before or after the amp?
I will post updates and pictures throughout the project if anyone is interested, maybe even a video. Here's a quick video I found of the picokeyer: http://www.youtube.com/watch?v=660WwT63I_Q
Thanks in advance,
Matt KC9QNC