Designing a switching circuit

In summary, Jason is looking for advice on a chip that can create an AC square wave and is working with a wide frequency range. He is also working on something that is classified as a weapon, but he does not mention what this is. He has found a setup that works and will post the circuit diagram once he tests it out.
  • #1
Jdo300
554
5
Hello All,

Can someone give me some suggestions for a chip that can drive some high frequency mosfets to create an AC square wave? I am designing a circuit that pulses the voltage from a capacitor into some coils I am working with but I need the square wave to be AC and not DC. I want to use mosfets to do this but I'm not sure how to switch it so that it will be AC.

Also, I am working with a rather wide frequency range for my experiments so whatever I come up with needs to be very adjustable (1KHz-7MHz). Even if I could come up with a couple of separate controllers that will cover the wide range, that would be fine too. I *think* that a 555 timer would work for the lower frequencies but what abut the higher ones?

Thanks,
Jason O
 
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  • #2
You could just to a quick and dirty inverter RC oscillator. Use something like an HC14 Schmidt trigger inverter, and put a resistor from its output to its input, and put a cap on its input to ground. Or you can use 3 inverters in a row (still just the one RC) to make it work a little cleaner. You adjust the RC time constant to get the frequency.
 
  • #3
I don't really know what an "AC" or "DC" square wave even means to you.

- Warren
 
  • #4
chroot said:
I don't really know what an "AC" or "DC" square wave even means to you.

- Warren

When I say AC square wave, I mean that the voltage changes from -V to +V rather than the DC square wave where the voltage changes from 0 to +V or 0 to -V.

@berkeman

Thank you very much for the information. I've never heard of a HC14 Schmidt trigger inverter. Could you give me some more info on it or maybe a good source link? Also, it would be very helpful if you could make a basic circuit diagram of what you are describing.

Thank you,
Jason O
 
  • #5
are u making a stun gun?It's tough making a clean high frequency signal due to capacitance in the wiring and leads.

if a signal goes from -5v to 5v, isn't it the same as 0 to 10v?
 
  • #6
david90 said:
are u making a stun gun?


It's tough making a clean high frequency signal due to capacitance in the wiring and leads.

if a signal goes from -5v to 5v, isn't it the same as 0 to 10v?

Hi David,

No I'm not working on any kind of weapons stuff. I'm experimenting with different obscure electrical effects such as the Barkhausen Effect, and electrostatic induction. Some of my tests involve the use of medium to high voltage spikes at specific frequencies. I will be experimenting with both the AC and DC square waves but so far, the AC ones seem to have the most pronounced effects.

Thanks,
Jason O
 
  • #7
Jdo300 said:
When I say AC square wave, I mean that the voltage changes from -V to +V rather than the DC square wave where the voltage changes from 0 to +V or 0 to -V.
You are not using standard terminology there. Both of the waveforms you are talking about are AC, since they are changing with time. One has a zero DC offset, and the other has a non-zero DC offset. DC means unchanging with time. You should try to use the standard terminology to avoid confusing others. (I'm not saying this to get on your case, I'm just trying to help you in your learning process.)

Jdo300 said:
Thank you very much for the information. I've never heard of a HC14 Schmidt trigger inverter. Could you give me some more info on it or maybe a good source link? Also, it would be very helpful if you could make a basic circuit diagram of what you are describing.
Like figure 8 in this Fairchild app note:

http://www.fairchildsemi.com/an/AN/AN-140.pdf#search="RC oscillator inverter schmidt"
 
  • #8
Hi berkeman,

Thanks for the correction about the DC offsets. As for the control circuit. I *think* I found a setup that will work. I'll post the circuit diagram for it once I finish testing it out. Thanks for all your help.

- Jason O
 

1. What is a switching circuit?

A switching circuit is an electronic circuit that allows the flow of electrical current to be controlled or switched on and off. It typically consists of one or more switches and other components such as resistors, capacitors, and inductors.

2. What factors should be considered when designing a switching circuit?

When designing a switching circuit, some important factors to consider include the type of load, voltage and current ratings, switching speed, power dissipation, and reliability. It is also crucial to ensure proper isolation between the control and power circuits to prevent any damage to the components.

3. What types of switches are commonly used in switching circuits?

The most commonly used switches in switching circuits are mechanical switches, such as toggle switches, push buttons, and relays. However, electronic switches, such as transistors and MOSFETs, are increasingly being used due to their smaller size and faster switching speeds.

4. How can I minimize the switching noise in my circuit?

Switching noise is a common issue in switching circuits, and it can be reduced by using proper decoupling capacitors, designing the circuit with shorter and wider traces, and using shielding techniques. It is also essential to select components with low parasitic capacitance and inductance to minimize noise.

5. Are there any design considerations for high-frequency switching circuits?

Yes, high-frequency switching circuits require special design considerations to ensure proper operation. These include using components with high switching speeds, minimizing parasitic capacitance and inductance, and selecting appropriate PCB materials with low dielectric loss. It is also crucial to carefully design the layout of the circuit to reduce high-frequency noise and interference.

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