# How do I created pulse DC at higher frequencies?

#### brainfarth

Joined Mar 4, 2022
5
How can I create pulse DC current and is adjustable from 60pps to the khz range @60v, 1amp max? I'm thinking of something similar to my TIG welder at work, which is capable of controlling not only the pulses per second, but the ramp-up and ramp-down times. I have a Ridon Rd6018 power supply, a generic 30v 5A DC power supply and a DIY unregulated adjustable 120v power supply to work with.
Thanks for any help.

#### Papabravo

Joined Feb 24, 2006
18,409
You build an oscillator with a square wave output having and adjustable frequency and duty cycle.
For adjustable rise and fall times you need a triangle wave oscillator with an output clamp to flatten the peaks

#### ronsimpson

Joined Oct 7, 2019
2,063
You build an oscillator with a square wave output having and adjustable frequency and duty cycle.
For adjustable rise and fall times
There are many ARB, wave form generators on the market from $100 to$3000 that will make any waveform you can draw. The one I have will work from 0.01hz to 60mhz. (30mhz is lower cost)

FY6900 60MHz Dual CH DDS Function Signal Generator, or
2 CH Programmable DDS Arbitrary Waveform Function Signal Generator PSG9080, or
Agilent Keysight 33522B Waveform Generator, 30 MHz, 2-Channel with Arb

That gets you a waveform at only 10 volts. Getting to 60 Volts is another thing.

#### brainfarth

Joined Mar 4, 2022
5
Could I use a FPA1000 Signal Power amplifier Module for Digital DDS Function signal Generator paired with the FY6900 60MHz Dual CH DDS Function Signal Generator to get up to 50v? I've been on the fence about the safety of handling 60vdc, so 50 might work.
I forgot to mention that the load is minimal, being in the mA range, <.3W

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#### ronsimpson

Joined Oct 7, 2019
2,063
FPA1000 Signal Power amplifier Module
Looks like it needs a +/-50V supply. Not a single 50V supply. It does not say but it might work with a +50V supply and a -12V supply if you don't care about the negative output.

#### MrChips

Joined Oct 2, 2009
26,089
You can use an LM675 power opamp which is good to 3A @ 60V.

#### brainfarth

Joined Mar 4, 2022
5
You can use an LM675 power opamp which is good to 3A @ 60V.
I ended up picking up a KKmoon FY6900-20M Function Signal Generator and some LM6675 opamps. Would you have a circuit idea to achieve a constant output voltage of 50v, up to 1A and able handle pulses anywhere from 20pps to 20khz? I cant have it wander over 50v with no load due to safety reasons.

#### sparky 1

Joined Nov 3, 2018
716
The pulse waveform for TIG is interesting. Notice the link below the trapezoid called pinch current helps in depositing the droplet.
The sound of the deposition rate will have a range related to globule size amperage and feed rate ect.

You can see the weld depiction below for each part of the waveform. There are different waveform controller designs.
The weld look called stacked dimes vs a full pedal concave look will have different wave forms.

The pinch follows the nature of electrical arc (plasma) with welding we have to go from an oscilloscope waveform
to a voltage current magnetic field depiction to get a general idea about pinch. Not as extreme with TIG but the distance from tungsten to the pool is too small the pinch could cause splatter and foul the electrode. The ionization potential and thermal conductivity is improved with helium.
Not withstanding the gas, it is when the temperature of the weldment is high sufficient then the weld runs smooth.
https://en.wikipedia.org/wiki/Pinch_(plasma_physics)

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#### brainfarth

Joined Mar 4, 2022
5
The pulse waveform for TIG is interesting. Notice the link below the trapezoid called pinch current helps in depositing the droplet.
The sound of the deposition rate will have a range related to globule size amperage and feed rate ect.

You can see the weld depiction below for each part of the waveform. There are different waveform controller designs.
The weld look called stacked dimes vs a full pedal concave look will have different wave forms.

The world of pulse MIG get way weirder than you might think. I worked for a place that welded aluminum with a push-pull MIG gun that not only pulsed the ARC but out push/pull the wire at the same time. The wire did not come out at a constant rate. I could leave a very narrow (3/16") weld bead on a butt joint and penetrate at least that deep. I dont know of any other method of welding that could match that result.
I TIG weld daily with pulsed DC for full-penn sanitary weldments for the high-tech industry. It helps keep the heat-creep down to a minimum.