Continue to Site

Welcome to our site!

Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

  • Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

LED/Buzzer combination help.

Status
Not open for further replies.

Rickkh

New Member
I get this circuit to work 'sometimes'
Can you see the problem??
what currents will be drawn?
 

Attachments

  • circuit2.JPG
    circuit2.JPG
    27.3 KB · Views: 184
C4 is backwards.
You don't say if the 555s are ordinary "high" current ones or Cmos ones that draw nearly no supply durrent.
You don't say if the U3 buzzer is a high current mechanical one or a low power piezo one.

The U3 buzzer messes up the input signal to the second 555. Connect U3 to pin 3 of the first 555 instead.
 
sorry about that, this is the right one I think
I am using 2 NE555's
 

Attachments

  • circuit2.JPG
    circuit2.JPG
    21.2 KB · Views: 156
I am glad you re-connected the buzzer to the proper position.

Didn't you look?
The datasheet for the NE555 shows its supply current is 5.5mA with a 9V supply. So two have a supply current of um, duh, 11mA. That is the "typical". The current might be more or less.

The operating current of the buzzer and the LED must be added.
 
I have always made sure pin 4 on a 555 is never left floating, if your are using a 'buzzer' as in self interupting vibrator you are going to have big problems.
 
Unless you add a diode in reverse parallel with it to absorb the back-EMF.

Most modern buzzer are either piezo or use a transistor oscillator to control the magnet so it shouldn't be a problem.
 
As a matter of interest, what are the dimensions of your probes ? And how much of the probe set will be submersed ?
 
Status
Not open for further replies.

Latest threads

New Articles From Microcontroller Tips

Back
Top