![]() ![]() ![]() 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. Once you find a tape formulation you like, use it exclusively. The reason they use 1khz is because 1khz is in the middle of the range of the human voice (100Hz-3Khz) and at 1Khz the power is at max and doesnt roll off dramatically like it does at higher frequencies. wait until there's a minute or three of tape on the take up spool or hub, then start. It goes on to talk about comparing your two speakers, and using it to test your cabling. 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. The simplest and free online tone generator for creating pure audio signals of any frequency from 1 Hz to 20000 Hertz (20 kHz), sine sound signal generator. You can substitute 20 Khz if the machine uses at least 1/2" tape and you are recording at 30 ips. The frequency of the master oscillator is given by the equation. The output frequency is programmable via a single resistor and the connection to its divider pin (labeled DIV). 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"). The LTC6900 is a 5 volt low power circuit available in an SOT-23 (5 pin) package. 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. The 700 Hz signal falls in the passband of an audio system and is easily distinguished from either 400 Hz or 1 kHz signals. 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. The ubiquitous NE5532 is about the slowest but is still 2 or 4 times faster than it needs to be for audio purposes.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. Note however that the 741 is the only chip around that is limited in that way. NOW that is! The humble 741 op amp will start to droop at 10kHz or so if you want 20dB of gain. Op amps can deliver any frequency you like from DC to the limit of their gain bandwidth product. Modern solid state electronics is pretty well 'aperiodic'. The start of tape recording and especially cassettes meant the 'pivot point' of the EQ curve was moved down to 300Hz iirc because 1kHz was already 'on the slope'. Then, back in the day when all we had was valves and transformers to amplify signals, one k was 'easy', below about 100Hz transformers start to droop and get more distorted and above 10kHz the higher impedance of valve circuits and cable capacitances began to lose you signal.ġ000Hz is not all embracing however. You can see that the 'cutting' / replay EQ curves pivots about 1kHz. That ^ was probably one reason 1kHz was chosen as a reference. ![]()
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