5 volt regulator question

Projects General Guidance
1

5 volt regulator question

I have this mc 7805ct regulator hooked up right now

The thing i noticed when i programmed the simple fm sketch and just had it set 1 station and that was it. I actually removed my uno from the breadboard circuit. Leaving only the tea5767 playing that station. It would keep going until i removed voltage from it.

Now here connected into this circuit i have the regulated 5 volt running the uno and the fm module. If i remove the uno from the battery (module still gets 5v) but the system goes quiet. But if i connect uno it comes back on.

But i had the uno 100% removed. I only plugged the 5 volt feed back into the uno. And the tuner came back on playing the station. It had not reset. But if i actually turn off the circuit from the battery it resets.

Just curious if its something to do with the regulator maybe it isn't set up correctly or something. The circuit tests at 4.9v although my 9v battery is running low. Although with a new 9v it tested at 5.1 v. Had the same issue.

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2

Image from Original Post so we don't have to download it. See this Simple Image Posting Guide

20200522_022711.jpg
20200522_022711.jpg1836×1836 825 KB

...R

3

A photo of your project does not provide the information needed to answer your question.

Please make a simple pencil drawing showing how everything is connected and post a photo of the drawing.

...R

4

Hi,
Look at the datasheet for the LM7805 and you will see they need a couple of bypass capacitors connected to the regulator leads.

Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?

Thanks... Tom... :slight_smile:

5

TomGeorge:
Hi,
Look at the datasheet for the LM7805 and you will see they need a couple of bypass capacitors connected to the regulator leads.

Can you please post a copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?

Thanks... Tom... :slight_smile:

Ahh. Maybe thats the issue. Do they make ones that don't require caps? I swear i had a couple that didn't. Ill have to patch that up and see if it clears up.

Right now the 5v regulator is just connected to the 9v battery and the output supplies circuit ground and 5v output to the tea5767 and uno vcc input pin to power it. Audio output to headphones for testing

Trying to make up a sketch that will work with the attiny85 chip. (New to that chip) i have gotten the blink sketch uploaded. Got the tinywire.h library. I had a sketch uploaded it didn't work but it may not have worked if it didn't power correctly like i found when i patched the uno in place of the attiny85 chip. I got the datasheet. Now i just got to dig out some caps for the regulator and try again

6

Robin2:
Image from Original Post so we don't have to download it. See this Simple Image Posting Guide

20200522_022711.jpg
20200522_022711.jpg1836×1836 825 KB

...R

This doesn't seem to work with mobile phone
And thanks for the link. Should work fine with the laptop. Im just usually on the phone more. Windows Vista is kinda slow on the internet.

7

Perfect. Doesn't cut out like it did. I can disconnect the uno and the tea5767 stays powered up. Looked into a few variations. Decided to go with a 100uf on the input 1 uf output. Cleared it right up. Power holding steady no funny business now. .

Funny the uno actually fits perfectly inside the factory battery compartment on this thing. May use it a little like that until i get the attiny85 working. Hopefully i can get the program figured out. Still a beginner on programming.

8

cserucsak:
Do they make ones that don't require caps?

No. :astonished:

cserucsak:
I swear i had a couple that didn't.

That indicates the caps were somewhere you could not see them. :roll_eyes:

9

nice

10

Paul__B:
No. :astonished:
That indicates the caps were somewhere you could not see them. :roll_eyes:

Maybe i am just losing it. I will keep that in mind now. Its been awhile that i have actually used a regulator in a made from scratch project. Usually either the component or project had already incorporated a voltage regulator. . like my previous version of this same circuit. Regulated through the uno or powered straight from a 5v connection. But with the addition of a 9v audio amplifier circuit and wanting to go with the attiny85 it was either 2 sources of power or a regulator for tiny85 and fm tuner chip.

Haven't made up a circuit in probably a few years actually.

Getting back into it. Im actually just surprised i got something to work today. And got the audio amplifier working on my own didn't really follow the schematic on that one. I did first but it didn't perform properly so i just went my own way with that until i got it working decent. (Could be better)

11

Hi,
The behavior of the LM series without the bypass capacitors depends on the load, sometime you will get away with no capacitors due to the performance of other circuit components.
But to play save and ensure consistent operation of the regulators the inclusion of capacitors is highly recommended.

Good to see your project is preforming, have you thought of a Nano or ProMini, rather than a ATtiny85?

Tom... :slight_smile:

12

TomGeorge:
Hi,
The behavior of the LM series without the bypass capacitors depends on the load, sometime you will get away with no capacitors due to the performance of other circuit components.
But to play save and ensure consistent operation of the regulators the inclusion of capacitors is highly recommended.

Good to see your project is preforming, have you thought of a Nano or ProMini, rather than a ATtiny85?

Tom... :slight_smile:

I have thought about a different approach. Having the FM programmed along with a (basic) SD card mp3 playback. Much more than that and i would have to basically move the project into a more suitable "device".

Right now its pretty basic FM only built into this old Wilson 2 way radio. Ive got the code running 1 analog input to control 4 "presets" and forward/back scanning of the tuner. The Wilson has a channel knob on top with 6 channels. Which i used the control to select a resistor . each a different rating but when that is constantly sensing the analog it interferes with the fm making a popping sound.. So i wired the 5v side through the "talk" button. So the analog stays pulled to 0 "ground" select what you want to do on the channel knob. Tap the talk button and it works. . it was after doing that, when i decided to put the search mode on 2 of the selections.. Theres only 1 actual button on this thing. But i got my "work around" working. I may remove one of the unused controls for a headphone output..

If i was to add a sd card mp3 playback. I would like to keep the controls working from the channel knob--tap the button configuration. Haven't decided if i would want to add some form of display .. Would like to keep it simple and not modify the outside of the unit.

The other thing i would like to lower the sensitivity on the tuner seek functions. It seems to only stop at high reception stations. And sometimes skips them.

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13

Hi,
In plain words and paragraphs can you tell us what you are trying to do and with what hardware please?
Are you aiming to Tx with the transceiver, if so do you have a license?

Tom... :slight_smile:

14

I am actually thinking about changing directions with this thing. Rebuilding a broken 1980s car stereo. Fitting an lcd going with a nano or something once i figure out how many pins i would need. Possibly running the audio feed into the original amplifiers within the Unit or using 2 tda7297 stereo amplifiers (front and rear) speakers. The wattage is fairly close to the oem amplifier circuit. But it would be newer hopefully better sounding. And either incorporating a digital or an analog equalizer circuit. Thinking about adding in wifi internet radio i can connect to my phones wifi hotspot to use. Sd card mp3 playback fm tuner circuit. While also having a switch to the factory cassette deck in the unit. (Yes i still use those). And also having a line output (for added amplifiers) subwoofer etc. Hookup capabilities.. I have a few fm tuner circuits so i may just wrap up this one simple fm tuner portable radio. Still trying to get the code to work properly on the tiny85. The tinywire.h library is a little different to get working..

15

TomGeorge:
Hi,
In plain words and paragraphs can you tell us what you are trying to do and with what hardware please?
Are you aiming to Tx with the transceiver, if so do you have a license?

Tom... :slight_smile:

This one is actually fairly simple besides me trying to figure out the attiny85 coding for the i2c tinywire.h library

The transceiver is simply the casing+speaker+controls to control a tea5767 FM module. With an ATtiny85. Small audio amplifier LM386N to run the speaker in the unit. Headphone jack added for "private listening" and the 5 volt regulator to supply everything except the LM386N currently running from a 9v battery. I may leave it run the 9v or change it to AAA batteries if space permits. Depending on battery lifespan.

Right now besides coding the tiny85 the analog "selector" circuit seems to be a little buggy. It kinda works with the uno i have run the serial monitor on the analog pin to test the analog readings. Coded each command about 15 numbers each direction of analog read results. May be possible the code is not done properly i will have to copy the code up. I figured using the analog read would turn the existing 6 position selector to function using 1 analog pin. Making the tiny85 be able to work the system. I can either get that analog read to work or lose the "preset" stations out and just use the 2 pins for tuning up or down. Or convert to a different controller and use all 6 selections as digital pins. Although i do believe the analog read can hopefully be worked out to function .. The selector control has 6 positions. It simply "closes a switch" to a common lead at each click. The talk button just completes the circuit through the common pin of the 6 position switch.

Reason for that is. I noticed that as long as (analogRead) is reading a signal within the parameters for it to change a station or seek a station it will constantly do that so i just reconfigured it that you select the function you wish to execute and tap the talk button. At which point the (analogRead) picks up the reading and executes the command by the time you release the button. At which point (analogRead) is referenced to ground to keep it at 0.

16

If this file is uploaded correctly (have not uploaded a code yet)

Its a work in progress. I started with the basic fm sketch and tweaked it some. If i can get the tiny85 to run a sketch this way with the analog read controller the LCD will be removed from the sketch. Not sure why i left bits of it in there

The issue is i don't get all of the controls functioning. I believe i have 2 presets that operate. And both search modes are working.

Plus im not quite sure how to lower the sensitivity on the search mode. It only seems to stop at high strength signals. Id like it to stop on anything that is audible .. The coil antenna seems to be pretty directional. If it would stop on a weak station i can simply re-position the unit to obtain better reception. Instead of blindly pointing different directions hitting the search button.

hguu.pdf (27.8 KB)

17

Hi,

Please read the post at the start of any forum , entitled "How to use this Forum".
OR
http://forum.arduino.cc/index.php/topic,148850.0.html.
Then look down to item #7 about how to post your code.
It will be formatted in a scrolling window that makes it easier to read.

Thanks.. Tom... :slight_smile:

18 
#include <TEA5767.h>
#include <Wire.h>
#include <Button.h>
#include <LiquidCrystal.h>

TEA5767 Radio;
LiquidCrystal lcd(12,11,10,9,8,7);
double old_frequency;
double frequency;
int search_mode = 0;
int search_direction;
unsigned long last_pressed;



void setup() {  
  Wire.begin();
  Radio.init();
  Radio.set_frequency(98.5); 
  Serial.begin(9600);
  lcd.begin(16,2);
  lcd.clear();
}

void loop() {

  unsigned char buf[5];
  int stereo;
  int signal_level;
  double current_freq;
  unsigned long current_millis = millis();
  
  if (Radio.read_status(buf) == 1) {
    current_freq =  floor (Radio.frequency_available (buf) / 100000 + .5) / 10;
    stereo = Radio.stereo(buf);
    signal_level = Radio.signal_level(buf);
    lcd.setCursor(0,0);
    lcd.print("FM: "); lcd.print(current_freq);
    lcd.setCursor(0,1);
    if (stereo) lcd.print("STEREO "); else lcd.print("MONO ");
    //lcd.print(signal_level);
  }
  
  if (search_mode == 1) {
      if (Radio.process_search (buf, search_direction) == 1) {
          search_mode = 0;
      }
  }
  
  if (analogRead(A2)>+580 && analogRead(A2)<650) {
    last_pressed = current_millis;
    search_mode = 1;
    search_direction = TEA5767_SEARCH_DIR_UP;
    Radio.search_up(buf);
    delay(300);
  }
  
  if (analogRead(A2)>+85 && analogRead(A2)<200) {
    last_pressed = current_millis;
    search_mode = 1;
    search_direction = TEA5767_SEARCH_DIR_DOWN;
    Radio.search_down(buf);
    delay(300);
  } 
  //delay(20); 
  delay(50);

  if (analogRead(A2)>+475 && analogRead(A2)<530) {
    Radio.set_frequency(105.7);
   }

   if (analogRead(A2)>+1000 && analogRead(A2)<1022) {
    Radio.set_frequency(96.1);
   }

 if (analogRead(A2)>+5 && analogRead(A2)<70){
    Radio.set_frequency(98.5);
 }
 if (analogRead(A2)>+5 && analogRead(A2)<70){
    Radio.set_frequency(95.3);
   }
   
}