A first test to find out if its practical to ‘piggyback’ external controls on to an existing radio. The reason for doing this is to leave an original radio intact by clipping the remote components to the leads of the existing controls.
For example a varactor would be connected in parallel to the variable capacitor already in the circuit. The existing capacitor would be set low. The capacitance of the varactor would then be added to the total, using the formula for parallel capacitors.
For potentiometers, its not as easy because parallel resistors are divided:
Formula: Rtotal = R1×R2/(R1+R2)
For example if R1 is 10K, R2 would need to be 100K to get a total resistance of 9K. To get 99% of the existing resistance, the piggyback resistor needs to be 100 times the value of the existing resistor. 1 MegOhm if matched with 10K.
What happens when the radio is not being controlled remotely?
For capacitance, the remote capacitor (varactor) should be set to 0.
For resistance, the remote resistor should be set as high as possible.
Conversely, how should the physical controls on the radio be set when operating remotely?
Variable capacitors should be set as low as possible.
Potentiometers should be set as high as possible. For a volume control this actually means turning the volume all the way down.
SPST switches can be considered as a form of potentiometer with infinite resistance. A piggybacked switch will only work if the existing switch is in the ‘off’ position. And vice-versa.
Double-Throw and Rotary switches present more difficulties as multiple states are maintained by the same device.
I don’t think multiple throw switches can be piggybacked. Two possible solutions:
mechanical connection to manual control (servo)
internal relays – requiring modification of the radio, so that the existing control and the remote control operate the same relays
Hybrid approach: Operate the switches manually while operating other controls remotely.
I piggybacked a tuning capacitor from an AM radio onto the tuning capacitor of a vintage Radio Shack Globe Patrol (regenerative receiver).
“… the design virtually eliminates the negative aspects of regenerative receivers such as antenna radiation, frequency pulling, micro- phonics and hand capacitance effects.” Ironically these are the features I am looking for.
An HTTP request transfers data to or from a server. A web browser handles HTTP requests in the background. You can also write programs that make HTTP requests. A program called “curl” runs http requests from the terminal command line. Here are examples: https://reactivemusic.net/?p=5916
Data is usually returned in one of 3 formats:
JSON is the preferred method because its easy to access the data structure.
Max HTTP requests
There are several ways to make HTTP requests in Max, but the best method is the js object: Here is the code that runs the GET request for the Vine API:
var ajaxreq = new XMLHttpRequest();
ajaxreq.onreadystatechange = readystatechange;
var rawtext = this._getResponseKey("body");
var body = JSON.parse(rawtext);
The function: get() formats and sends an HTTP request using the URL passed in with the get message from Max. When the data is returned to Max, the readystatechange() function parses it and sends the URL of the most popular Vine video out the left outlet of the js object.
Playing Internet audio/video files in Max
The qt.movie object will play videos, with the URL passed in by the read message.
Unfortunately, qt.movie sends its audio to the system, not to Max. You can use Soundflower, or a virtual audio routing app, to get the audio back into Max.
Using the text processing example I built a 4th order Markov chain for “The Cat in The Hat” (by Dr. Seuss). Here is some of the result (it continues to infinity) with indentation added for readability:
The sat the sun is not shine.
It was to Sit! Sit!
And I sat in the house
How I wish We had something went BUMP! How I wish We did not shine.
It was to us jump! We looked!
The Cat in that cold to go out And wet to play.
So all we sat in the Hat! And he saw him!
Then we sat is wet to Sit! Sit!
And to go out
And the house
Why do was too wet And there little bit. And wet to go out
And there we saw him step in on that?
How I wish We sat is nothing at all.
So all we could do was too wet day.
So all we sat the house
All that is fun there we can have Lots of good fun the mat!
We had something at all.
So wet to go out And the sun is wet to Sit! Sit!
And I said too wet to do I know it is not sunny!
Too we can have Lots of good funny!
Too wet And I sat is fun the house. We sat the house. We saw him!
The Cat is wet to us.
The help file patch allows real time Midi improvisation with a step sequencer style of playback: