No, no reeds.
Reuter always used the Schumacher tone filter circuit.
Similar to this circuit, but with 2 filter stages.
Clever use of the transistor as a tuned AC amp and then again as a DC switch.
I used Reuter's pot cores and capacitor sets to build my first RC set from scratch, a 2 channel tone filter unit.
Got it working, though never enough range (being age 17, I had no clue about HF back then).
In hindsight the oscillator probably wasn't feeding enough signal to the power stage...
Hence not driving it into saturation, eventually killing any Class C stage.
I blew up several AF 118 while trying to improve this.
After 3 fly aways I had enough and started on a Classic Custom that ended up with almost the same range...
But then with the telescope antenna all the way in.
A few years back I had the plan for making a 27 MHz receiver with a simulated tone filter bank.
I tweaked an Arduino sketch for a telephone touch pad decoder so it actually responded to the 1080 an 1320 Hz tones.
Then I discovered the HF brick from the Rehaton 10 I have here also didn't work. So the project was grounded....
#include <Goertzel.h>
int sensorPin = 4; //nog checken!!!!!!
const int N = 100; //it is the number of samples code will take y0u can change for sensitivity and can if large it can slow the arduino
const float threshold = 2000; //minimum tone amplitude to be considered we can change it for more senstivity
const float sampling_freq = 8900; //maximum detectable frequency is the sampling rate/2 and arduino uno with 16Mhz can support sampling upto 8900 Hz
float frequency[2]; //make an array for channel frequencies to be detected
int channel;
int ch;
int reset = 0;
void setup(){
pinMode(1, OUTPUT); //initalize blink led to show if any tone is detected
pinMode(2, OUTPUT); //initialize 2 pins as output to show the channel outputs from 2 to number 3
pinMode(3, OUTPUT);
frequency[0]=1080; //just initialize the array with the tone frequencies along with their number
frequency[1]=1320;
}
bool detect_tone(float freq){
Goertzel goertzel = Goertzel(freq, N, sampling_freq); //initialize library function with the given sampling frequency no of samples and target freq
goertzel.sample(sensorPin); //Will take n samples
float magnitude = goertzel.detect(); //check them for target_freq
if(magnitude>threshold) //if you're getting false hits or no hits adjust the threshold
{
return true;
}
else
return false;
}
void loop(){
int i=0;
while(1){
if(detect_tone(frequency
) == true){
channel = i;
break;
}
i++;
if(i==3)
i=0;
}
//find the number corresponding to the found channelfrequency
if(channel== 0)
digitalWrite (2,HIGH);
if(channel== 1)
digitalWrite (3,HIGH);
delay (100);
if(detect_tone(frequency) == false)
digitalWrite (2,LOW);
digitalWrite (3,LOW);
}