So, for a very slow clock of 1 Hz (1 cycle per second), the period is 1 second. The period of a clock is the time taken for one cycle. The frequency of a clock is the number of complete cycles (0 to 1 back to 0 again) per second. Division by anything except powers of 2 (1, 2, 4, 8, 16, etc.) in Verilog is not possible without the use of a division module and would require more than one clock cycle to perform. The reason that the period is used rather than the frequency is that to convert the frequency to a number of clock cycles to count in Verilog would require division (see the sidebar “Frequency and Period”). A parameter CLK_F is used to configure the module’s prescaler to suit the clock frequency of your board. The tone module has inputs of the system clock (CLK) and the period of the tone to be generated in microseconds and a single output of tone_out. If you don’t, then change the location (LOC) of one of the “tone” NETs to your audio jack as per the “alarm” project and listen to the tones through your amplifier-although you may struggle to hear the 12.5-kHz tone. If you have an oscilloscope or multimeter with a frequency setting, then you will be able to verify the signal being generated. Rather than play the generated frequency through the audio jack, the test program for this module will generate three different frequencies on three different pins of the FPGA board. See Chapter 2 for instructions on downloading the code for this book. You can find the project directory for this module in the downloads for this book in the directory ch08_tone. To improve it, we can make a general-purpose tone-generator module that will be parameterized for the clock frequency of your board and will also allow you to specify the tone to generate as one of its inputs. Every tape formula has a distinctive smell and some brands carry a distinctive family smell it's relatively easy to learn how to identify a tape formula by smell alone by storing a reel of tape in a plastic bag as well as the box and just just sniffing the bag storing the tape.The “alarm” project is about as simple as tone generation gets. Once you find a tape formulation you like, use it exclusively. wait until there's a minute or three of tape on the take up spool or hub, then start. Grab some tape before you attempt a bias setting ie don't use the tape at the start of the hub or reel. Ideally the playback will show the same Vu level as the record, but somewhat more important is the playback levels of the two tones relative to each other. Record the two bias setting tones at -20Vu (cassette) -10Vu (consumer tape deck) or 0Vu (professional tape deck). A 1 Khz tone can also be useful, however. 400 Hz is a good second tone, you only use the two. You can substitute 20 Khz if the machine uses at least 1/2" tape and you are recording at 30 ips. Stay tuned, if anything works I'll draw it up on that original thread.Īn upper limit for bias tone generator would be 10 Khz for any 1/4" tape machine or smaller (eg cassette 1/8"). I'm trying to fly the drill it yourself lexan board over the mcmelecttonics pcb, but holiday preparation has got in the way. I've got some new $.85 DIP project boards from mcmelectronics, the DIP socket fits and solders fine but there is no room on it for the 15 discrete parts involved. I have been trying to get it packaged with test circuit 12 on the datasheet () but I've mostly proved solder sticks better to drill it yourself lexan and beigh CB boards than it does to socket pins. You can still get the IC in DIP package for $6 at. The Exar XR2206 sine wave generator IC looks to be a lot more professional, but the nifty kit that was built on top of this is long gone. BTW, the power supplie I have dedicated to this is a 4 amp 12 V CT battery charger transformer on an open frame that produces 19.5 V full wave rectified (1500 uf cap) or 9.5 V half wave rectified (2200 uf cap) both using the minus rail as reference. The GE circuit is not producing any tone I can hear through the amp I'm trying to repair, that does play a transistor radio a bit into a speaker before motorboating. Don't know if the 6 mv was ~800 hz (with. Have tried both 2n2905 at reversed polarity, and 2n3904 with as drawn polarity so far, got 6 mv out a little while but the o-scope sweep quit, I guess it blew the power supply. I'm trying to build a 2 transistor oscillator from the GE Transistor manual 7th edition, it worked with a lot of hum imposed but when I put enough capacitance on the rail to get rid of the hum it just sits there. The EDN link for an amplitude stable oscillator leads to some op amp circuit using an op amp I don't have. Check out this link for a build it yourself: The Eliot project has way too many parts for my taste, a split supply which is another 6-9 parts, plus some weird light bulb I don't have as a PTC Resistor.
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