Help getting plus and minus 6 volts (square wave)out of 9VDC

[mramos1]

Would this follow the way it works with a transistor?

 

[Roff]

Would this follow the way it works with a transistor?

Yes. A CMOS inverter would require less power, but it may be insignificant. With the BJT, you can use large value resistors if you are running at 7Hz and you are wanting 10Meg impedance at your outputs.

 

[mramos1]

Would this follow the way it works with a transistor?

Yes. A CMOS inverter would require less power, but it may be insignificant. With the BJT, you can use large value resistors if you are running at 7Hz and you are wanting 10Meg impedance at your outputs.

Yes on the 10 meg output.

I also was going to use a 556 and run it for 20 minutes. So a CMOS chip and that would be 2 chips and save battery. Or throw out the 556 and use AVR Tiny uC to pulse it and go to sleep in 20 minutes. What are your thoughts on the uC over the timer. The code is already done. And I can blink an LED and have a switch for 2 settings.

 

[Roff]

Would this follow the way it works with a transistor?

Yes. A CMOS inverter would require less power, but it may be insignificant. With the BJT, you can use large value resistors if you are running at 7Hz and you are wanting 10Meg impedance at your outputs.

Yes on the 10 meg output.

I also was going to use a 556 and run it for 20 minutes. So a CMOS chip and that would be 2 chips and save battery. Or throw out the 556 and use AVR Tiny uC to pulse it and go to sleep in 20 minutes. What are your thoughts on the uC over the timer. The code is already done. And I can blink an LED and have a switch for 2 settings.

I hope someone else will comment on this. I don't have experience with microcontrollers.

 

[Nigel Goodwin]

If you have micro-controller experience, then it's simple enough to use a micro-controller. You can even use two output pins to give your bridged output directly (I modified a PIC magazine project like this, in order to give more power to a piezo beeper).

However, the output will be plus/minus the supply rail of the micro, which is normally only 5V?.

 

[mramos1]

If you have micro-controller experience, then it's simple enough to use a micro-controller. You can even use two output pins to give your bridged output directly (I modified a PIC magazine project like this, in order to give more power to a piezo beeper).

However, the output will be plus/minus the supply rail of the micro, which is normally only 5V?.

Do you have this circuit on your website. I am very good with PIC and AVR, unfortunatly, it has caused me to be rusty now in analog design. There is a AVR Tiny of some type that is $.50. I was going to use that. it has 6 IO pins. One will select the Hz, one to blink the LED, and for sure 2 left to pulse. I am not sure one how I will hook the uC up and get plus and minus, but today I will write the code and dig out a breadboard. Can't I use LM7805 to run uC and then transistors to drive the plus minus off the 9V battery?

 

[Nigel Goodwin]

Do you have this circuit on your website. I am very good with PIC and AVR, unfortunatly, it has caused me to be rusty now in analog design. There is a AVR Tiny of some type that is $.50. I was going to use that. it has 6 IO pins. One will select the Hz, one to blink the LED, and for sure 2 left to pulse. I am not sure one how I will hook the uC up and get plus and minus, but today I will write the code and dig out a breadboard.

It's simple, assume you have 2 pins, pin1 and pin2.

Make pin1 HIGH and pin2 LOW.

Delay required time

Make pin1 LOW and pin2 HIGH

Delay required time

Loop

Can't I use LM7805 to run uC and then transistors to drive the plus minus off the 9V battery?

Yes you can!.

 

[mramos1]

It's simple, assume you have 2 pins, pin1 and pin2.

Make pin1 HIGH and pin2 LOW.

Delay required time

Make pin1 LOW and pin2 HIGH

Delay required time

Loop

Got that part, but have inverter, R and C on pin1 and RC on pin2. That will get me plus and minus 10v peak to peak? That will work if the case.

 

[Nigel Goodwin]

It's simple, assume you have 2 pins, pin1 and pin2.

Make pin1 HIGH and pin2 LOW.

Delay required time

Make pin1 LOW and pin2 HIGH

Delay required time

Loop

Got that part, but have inverter, R and C on pin1 and RC on pin2. That will get me plus and minus 10v peak to peak? That will work if the case.

Yes, an inverter will work the same, but if you're using a micro-controller you don't need one.

 

[mramos1]

Ron H and Nigel, Thanks so much. Took 30 minutes of coding, and 15 to breadboard, and exactly what I wanted. That bridge thing works well. I get 10 volts p-to-p on the nose. Thanks again. in circuit is uC, 4 Rs, a switch, LED, battery. And poof.. Now to put it on my sore back...

 

[Nigel Goodwin]

And poof.. Now to put it on my sore back...

Can't help you there! - it's rather controversial if it works ot not?.

 

[mramos1]

If you know were to put the probes (and I do not, hahaha) it works well..

 

[mramos1]

Nigel, is there anyway I can get a 0 to -5V (cut out the +5v part) squarewave by pulsing the pins on the uC?

 

[Nigel Goodwin]

Nigel, is there anyway I can get a 0 to -5V (cut out the +5v part) squarewave by pulsing the pins on the uC?

Use the pin of the uC as 0V output, and the Vss pin as the output.

 

[mramos1]

Right now I have Pin1 and Pin2 two, and I pulse them alternatly and I get plus and minus 5volts out, I would like to be able to flip on the fly to switch off the plus 5 on the same two pins. Not sure if the bridge type pulsing will allow this. I guess I could switch VSS (that is ground one the battery) to one of the pin2 via a transistor, but that will make for a -5volts?

 

[Nigel Goodwin]

Right now I have Pin1 and Pin2 two, and I pulse them alternatly and I get plus and minus 5volts out, I would like to be able to flip on the fly to switch off the plus 5 on the same two pins. Not sure if the bridge type pulsing will allow this. I guess I could switch VSS (that is ground one the battery) to one of the pin2 via a transistor, but that will make for a -5volts?

Easiest way would be a simple SPDT toggle switch - but why would you want to do this?.

You could also just do it in software, stop toggling one of the pins and set it high or low.

 

[mramos1]

Right, that was what I wanted to do, but was not sure if it would go negative.
I have Pin1 NEG and Pin2 POS, just stop pulsing Pin2.
Will try that tonight.

 

[Nigel Goodwin]

Right, that was what I wanted to do, but was not sure if it would go negative.
I have Pin1 NEG and Pin2 POS, just stop pulsing Pin2.
Will try that tonight.

Just stop pulsing Pin2, and set it HIGH, the other pin will then pulse negative with respect to Pin1. If you set Pin2 LOW, then Pin1 will pulse positive.

 

[ehsanbehroozy]

hello

what do you job?