Then you could use your original idea using 7 555s for the reasons you mentioned.

The other reason I like to use individual 555s is their indicating lights with different colors. With each light ON, its possible to know what frequency it is ON this feature will be very useful.

 

Like I said above I like to have discrete circuits so that failure of one does not pose significant impact on the entire circuit.

But you are creating that failure possibility by having discrete circuits and multiplying the failure rate by every component you add. The most reliable circuit is the one with minimal parts...

All you need here is a variable pulse rate generator and a power switch x 1, no more, no less. 1 8-pin MCU & 1 MOSFET, thats it. In the video I changed 0.1Hz to 2Hz and the higher frequencies you can't see except for their 'beat effect' with 25 frames/sec

The other reason I like to use individual 555s is their indicating lights. With each light ON, its possible to know what frequency it is ON this feature will be very useful.

Well you could add static LED for each frequency, or a 7-seg display showing numbers 1-7, or a little OLED screen showing the frequency... or... or ...

 

Here is an idea.

You could use a 7 input OR gate with a buffered output, connected to the outputs of the 555s.

Then it may be possible to control which 555 is active by using the 4017 connected to the reset pins of the 555s.

We already discussed in another thread and we decided to switch the power supplies instead of the 555 output due to the series resistance it poses to the output.

 

We already discussed in another thread and we decided to switch the power supplies instead of the 555 output due to the series resistance it poses to the output.

There would be no series resistance with this concept.

The output from the OR gate would be buffered, and that output would go to your switcher.

This idea uses no MOSFETS or CD4066 or such, and the final output would be from a good rail to rail Op-Amp.

 

The other reason I like to use individual 555s is their indicating lights with different colors. With each light ON, its possible to know what frequency it is ON this feature will be very useful.

LEDs can be added to the output of the 4017 to indicate the frequency.

 

Irving,

Yes I agree with whatever you say is right. It would get very simple with an MCU and the DMC 4050 I understand. I have to learn MCU programming. Major part have to do is to write a program to give pulsing outputs at a single output pin of the MCU sequentially at 1 hour time interval changing frequencies. Now I am in learning and testing stages using discrete ICs. Thanks for the circuit.

I suppose this is the DMC 4050 you mention. This one isn't readily available in my place like the other ICs but I will be able to get it.

 

Here is my one 555 concept.

The clock is just a pulsed voltage source for the sim...replace that with whatever you choose...555, CD4060...whatever.

The 4017 selects the "upper" 555 resistor. The resistors shown can be replaced with trim pots.
The resistor and capacitor values are just random picks...use the values as needed.
The 4013 converts the output to 50/50 duty cycle.
The Op-Amp buffers the output.
Power connections to the 4013 and 4017 not shown.

LEDs can be added to the 4017 outputs if desired...not shown.

 

Here is my one 555 concept.

The 4017 selects the "upper" 555 resistor. The resistors shown can be replaced with trim pots.

So I can change the frequency just by changing the upper resistors and keeping lower resistor and capacitor values unchanged. The duty cycle can be altered to 50/50 using the 4013. Sounds good, initially I had a concept or idea about switching the resistors but gave up.

Could you give the name of the OP AMP IC used for this.

 

This is the general idea of how an OR gated 555 output scheme would look like, using a 4017 to select.

So I can change the frequency just by changing the upper resistors and keeping lower resistor and capacitor values unchanged. The duty cycle can be altered to 50/50 using the 4013. Sounds good, initially I had a concept or idea about switching the resistors but gave up.

Yes, but you must adjust the frequency because the 4013 is a divider.

 

I used the AD822 model Op-Amp in the sim, but that was only for the sim.

You would choose any suitable model.

Rail to Rail
Unity stable
Voltage range needed
Single supply
Output current needed

Someone more familiar with common Op-Amps can probably give you an answer, but you may need to provide more info on what it will be driving.

 

Here is an idea.
You could use a 7 input OR gate with a buffered output, connected to the outputs of the 555s.
Then it may be possible to control which 555 is active by using the 4017 connected to the reset pins of the 555s.

I think I will go about with the OR gate concept because I already have the 7 circuits made separately in hand now with different indicating lights, resistors and capacitors calculated for each frequency. But how would you control which 555 is active using a 4017 connected to the reset pins of the 555 ics. Would the reset pin power OFF and ON the ics.

Thanks.

 

I think I will go about with the OR gate concept because I already have the 7 circuits made separately in hand now with different indicating lights, resistors and capacitors calculated for each frequency. But how would you control which 555 is active using a 4017 connected to the reset pins of the 555 ics. Would the reset pin power OFF and ON the ics.

Thanks.

No, the reset pin just places the 555 in a "hold" mode when in astable mode, with the output held "LOW".

You would connect the outputs of the 4017 directly to the reset pins of the 555s.

When any output is HIGH that 555 will be active, when any output is LOW that 555 will be inactive and the output will be held LOW.

 

Just to whet your appitite, and show why, once you use an MCU, you don't go back...

 

Just to whet your appitite, and show why, once you use an MCU, you don't go back...

That's amazing. Sure once I go into MCU I wouldn't go back.

Reason now I m after chips is I like to have a discrete component version of this project for back up and emergency purpose. Then I would start the MCU version and sure I wouldnt go back.
Thanks for the video.

 

That's amazing. Sure once I go into MCU I wouldn't go back.

Reason now I m after chips is I like to have a discrete component version of this project for back up and emergency purpose. Then I would start the MCU version and sure I wouldnt go back.
Thanks for the video.

What makes you think a discrete circuit trumps what Irving suggested?

That's amazing. Sure once I go into MCU I wouldn't go back.

Reason now I m after chips is I like to have a discrete component version of this project for back up and emergency purpose. Then I would start the MCU version and sure I wouldnt go back.
Thanks for the video.

It would help members if you gave a full description of your project. The pseudocode is important even if you don't decide to use a microcontroller.

The important thing is to get the algorithm correct. Then members much more experienced than myself can give you effective advice.

Too often I see folks post too little details about their project. Without knowing the criticality of the project, how can members advise to your specific safety requirements? Food for thought.

 

What makes you think a discrete circuit trumps what Irving suggested?



It would help members if you gave a full description of your project. The pseudocode is important even if you don't decide to use a microcontroller.

The important thing is to get the algorithm correct. Then members much more experienced than myself can give you effective advice.

Too often I see folks post too little details about their project. Without knowing the criticality of the project, how can members advise to your specific safety requirements? Food for thought.

About that last remark: Truer words seldom spoken. ADEQUATE Information reduces guessing. And speeds the trip to the right answer.

 

About that last remark: Truer words seldom spoken. ADEQUATE Information reduces guessing. And speeds the trip to the right answer.

It's also important for us as team members to foster the process of discovery. I find most folks aren't good at expressing themselves and that's no shame to themselves, semantics is a tough business. For a while, I've been focusing on what is not present in someone's argument or post and then I call attention to it. I've found many people are able to correct their own mistakes or simply become aware where they are weak if they are guided in a similar neutral way.

This technique also helps me review what I know and don't know about the user's question. About an hour ago I misread ECU as MCU! Right off the bat, I'm out of scope on half my post because I don't know much about automotive!

 

At three different jobs, part of my contribution was to not only develop the concept of our package but to provide the descriptions of what would be provided and what would not be provided. To do that I had to know what was needed even better than the folks who would buy the machine, on some occasions. So I often had to ask some questions. That is why I ask now, because otherwise it may only be a guess, and it might be a wrong guess. Often it takes a few people to pull off a terribly wrong guess.

 

Why are people reluctant to try something different?

1) because they would be walking into unfamiliar territory,
2) because they are uncomfortable stepping outside of their comfort zone.

Do it for yourself and you will be happy and thankful that you did it!

 

What makes you think a discrete circuit trumps what Irving suggested?

It would help members if you gave a full description of your project. The pseudocode is important even if you don't decide to use a microcontroller.

The important thing is to get the algorithm correct. Then members much more experienced than myself can give you effective advice.

k1ng 1337 and MisterBill2,

The reason is I am powering an electromagnet. I checked that the maximum value was 2500 uTesla. I suppose it is safe. Still prolonged exposure I am not sure since it runs 24/7. I am not sure if a microcontroller can operate in close proximity to the electromagnet. Or I have to put the MCU at a different location and run wires to the electromagnet. In any case I like to have a discrete component setup before trying out the microcontroller.

My project is not commercial, I am not selling anything. I am only building this for personal use. If I go into the details then that would make me sound like a con. I am trying to develop a magnetoculture like setup to heal the body by targeting the chakras of the body at various frequencies. And as said before its only for my own personal use not commercial.