banding NANDing

THE LATHE, aka: LS-76, by L. J. Scully

banding NANDing

Postby Andrew » 15 Apr 2017, 17:52

The truth table for a NAND gate is as follows:

A____B____X

0____0____1

1____0____1

0____1____1

1____1____0

Basically, if either the A input or the B input is NOT high (as in, below 2.5 V and, therefore, a logical: 0), then the output, X, will be high (i.e., above 2.5 V and, therefore, a logical: 1). If both the A input and the B input are high (as in, above 2.5 V and, therefore, a logical: 1), then the output, X, will be low (i.e., below 2.5 V and, therefore, a logical: 0).

I recently looked into remoting the banding of THE LATHE (so that it would be easier to initiate a "band" command (manually) while changing eq settings in between songs, since that requires standing at the console during a cut, rather than remaining at the lathe). "Banding" is the function that causes the feed to expand suddenly for, either, a manually, or automatically, specified amount of time, in order to create a visible space between songs on a given side - allowing for ease of cueing. "Bands" are the selections (or songs), while "banding" is the creation of space between the bands...

I found a logic gate output state calculator, online https://academo.org/demos/logic-gate-simulator/, which explained, visually, how the arrangement of NAND gates in THE LATHE's control circuitry allows the Band pushbutton to work the same, whether or not the remote control panel is connected, even though, when it's not connected, one of the pull-up resistors that normally gets its current pulled down, due to being normally closed to ground on its switch, is not grounded, and, therefore, the voltage pulls up the associated input pin, altering the logic state of that part of the circuit, without altering the logical conclusion of the entire circuit. The photos shown, below, illustrate THE LATHE''s Banding NANDing.

In this situation, the remote control panel is not attached to the back of the lathe, so, both pull-up resistors for the bottom, two NAND gates keep the inputs high.
BandingNANDingOFF(sansRemote).jpg
BandingNANDingOFF(sansRemote).jpg (53.1 KiB) Viewed 99 times



In this situation, the remote control panel connector is still not attached to the back of the lathe, but the Band (double-pole, single throw) pushbutton on the main console control panel has been pushed, "breaking" the ground that normally steals the pull-up resistor's voltage for the top gate's upper pin, bringing it to logical: 1, while also "making" a ground (on the other pole), momentarily, which steals the pull-up resistor voltage from the second gate's lower pin, bringing it to logical: 0.
BandingNANDingON(sansRemote).jpg
BandingNANDingON(sansRemote).jpg (64.29 KiB) Viewed 99 times




In this situation, the remote control panel is attached to the back of the lathe, and, therefore, the pull-up resistor current for the top pin of the third gate is connected to ground (due to the nature of Normally-Closed contact on the double-pole, single-throw switch to which it is attached), bringing it to logical: 0, since the shunted current results in voltage not being seen by that gate's input (at all). However, the logical conclusion of the NAND circuit has not changed from that of the first situation listed, above, when the remote control panel connector was not attached to the back of the lathe, and, therefore, the pull-up resistor voltage was seen by the target pin.
BandingNANDingOFF(Remote).jpg
BandingNANDingOFF(Remote).jpg (63.52 KiB) Viewed 99 times


And in this situation, the remote control panel initiates banding.
BandingNANDingON(Remote).jpg
BandingNANDingON(Remote).jpg (63.15 KiB) Viewed 99 times




- Andrew
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Re: banding NANDing

Postby Andrew » 15 Apr 2017, 18:18

Now, implemented... The image, below, shows that the Neumann SP272 console has been given* a new pushbutton, right underneath and in between the two Sifam VU meters. This pushbutton (with an orange, rectangular lens, illuminated by a 30V slide base bulb that is fed by the same 24V supply that illuminates the VU meters...) is a double-pole, single throw, momentary contact switch that remotely can initiate banding while the lathe feed is turned on. This way, I can stand at the console, where the switches for the equalizers are, and, when one song ends, be in position, both, to invoke the Band command, and to change the gain, or frequency, of the desired eq change. Hitherto, I had been forced to pivot between THE LATHE and the console. Every fraction of a second counts...


Remote possibility:
Remote_Banding.jpg
Remote_Banding.jpg (118.27 KiB) Viewed 70 times


* the hole for the new pushbutton was already there, in the SP272 frame, of course. I had a single-throw, momentary contact, there, previously, like the other two, shown.


servus,
Andrew
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Joined: 03 Apr 2013, 03:13


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