How to realize forward and reverse pulses

QWE4562009

How to realize forward and reverse pulses [Copy link]

 

Implementation methods of positive and reverse pulses 1. What are the differences between open-drain output, push-pull output, and full-bridge output? 2. Are drain output and open-drain OD output the same concept? Are push-pull output and half-bridge output the same? 3. For the load, there is no positive or negative. To truly achieve the output of positive and negative voltages, the premise is that the power supply must be a positive and negative power supply system? 4. The H-bridge drives the motor forward and reverse, but the direction of the current is different. There are not positive and negative voltages at both ends of the motor? 5. If you want to output positive and negative pulses (as shown in the figure), do you have to use positive and negative power supplies? I see that the sample does not use positive and negative power supplies, and it can also output positive and negative pulses, as shown in the waveform in the figure. 6. What are some simple ways to achieve the output of this waveform? (The output current waveform is an asymmetric, rectangular dual-band waveform, and the modulated current waveform is a trapezoidal wave) There should be no need for a DDS/signal generator circuit, right? This will increase the cost, and it may not meet the requirements, because after all, it is a single step wave/sparse and dense wave

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Whether pull-up is needed is the difference between open-drain output and push-pull output

Push-pull does not require pull-up

qwqwqw2088

To achieve positive and negative voltage output?

This waveform output?

DSP can achieve

The microcontroller can also achieve low frequency

QWE4562009

qwqwqw2088 posted on 2022-3-5 19:12 To truly realize the output of positive and negative voltages? Need this kind of waveform output? DSP can achieve single-chip microcomputers can also achieve...

How to implement single chip microcomputer

The working principle of a microcomputer low-frequency pulse therapeutic device
https://tech.hqew.com/news_1119064
Is this feasible?

Gen_X

If it is a dual power supply, a push-pull output to ground can be achieved;

If it is a single power supply, it can only be achieved using the H-bridge method.

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Gen_X posted on 2022-3-20 22:12 If it is a dual power supply, push-pull output to ground can be achieved; if it is a single power supply, it can only be achieved using the H-bridge method.

I'm using a single power supply.

If it is a dual power supply, a push-pull output to ground can be achieved;

If it is a single power supply, it can only be achieved using the H-bridge method. I don't understand, can you explain it in detail?

QWE4562009

Gen_X posted on 2022-3-20 22:12 If it is a dual power supply, push-pull output to ground can be achieved; if it is a single power supply, it can only be achieved using the H-bridge method.

Isn't it also possible to add output capacitors to a half-bridge? Similar to an amplifier

Gen_X

QWE4562009 posted on 2022-3-23 18:53 Isn't it also possible to add output capacitors to a half-bridge? Similar to an amplifier

Of course you can, but the edges will be deformed, and there will be very small edge distortion depending on the frequency.

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Gen_X posted on 2022-3-23 20:27 Of course it can, but the edges will be deformed, and there will be slight edge distortion depending on the frequency.

I just need to output low frequency. What size capacitor should I choose for this frequency? Currently, CBB is selected. It has better frequency characteristics, small dielectric loss, wide response range, high insulation impedance and no polarity.

Gen_X

This is a bit difficult. Because the lower the frequency, the larger the capacitor is needed. For voltage signals, 100Hz requires at least 100uF non-polarized capacitors. To ensure that it is not true.

Therefore, electrolytic capacitors and diodes are generally used to connect into a "non-polar" capacitor.

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Gen_X posted on 2022-3-25 09:31 This is a bit difficult. Because the lower the frequency, the larger the capacitor required. For voltage signals, 100Hz requires at least 100uF non-polarized capacitors. To ensure that it is not...

I have now made two solutions; one is half-bridge + CBB output capacitor, connected to the OTL amplifier mode

Another solution is to use four transistors to make an H-bridge. We'll see which one works better.

How do you calculate the capacitance of 100UF corresponding to 100HZ? f=1/2πRC? R is an unknown number. How do you calculate C?

Gen_X

It depends on the nature and situation of your load. It can be calculated, but we basically don't do it. We hire estimates based on experience.

QWE4562009

Gen_X posted on 2022-4-2 09:31 It depends on the nature and situation of your load. It can be calculated, but we basically don't. We hire estimates based on experience.

The load is the human body impedance, which is about 1K, and the stimulus circuit is within 50mA. How did you determine the output capacitor of your half-bridge to be 100UF?

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Gen_X posted on 2022-4-2 09:31 It depends on the nature and situation of your load. It can be calculated, but we basically don't. We hire estimates based on experience.

2-100Hz, take the value 2HZ, the load impedance is 500Ω, C=1/2/3.14/500/2, which is 159uF

QWE4562009

Implementation methods of positive and reverse pulses

1. What are the differences between open-drain output, push-pull output, and full-bridge output?

2. Are drain output and open-drain OD output the same concept? Are push-pull output and half-bridge output the same?

3. For the load, there is no positive or negative. To truly achieve the output of positive and negative voltages, the premise is that the power supply must be a positive and negative power supply system?

4. The H-bridge drives the motor forward and reverse, but the direction of the current is different. There are not positive and negative voltages at both ends of the motor?

5. If you want to output positive and negative pulses (as shown in the figure), do you have to use positive and negative power supplies? I see that the sample does not use positive and negative power supplies, and it can also output positive and negative pulses, as shown in the waveform in the figure.

6. What are some simple ways to achieve the output of this waveform? (The output current waveform is an asymmetric, rectangular dual-band waveform, and the modulated current waveform is a trapezoidal wave) There should be no need for a DDS/signal generator circuit, right? This will increase the cost, and it may not meet the requirements, because after all, it is a single step wave/sparse and dense wave

qwqwqw2088

Being able to ask so many questions and find so many relevant pictures

We are almost halfway through the problem.

What is missing is the use in actual products