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PhenixRising
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Joined: 07/11/2023
Location: United Kingdom
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Posted: 02:03pm 21 Mar 2025

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Mixtel90 said This is why using a linear regulator helps, there is far less supply
line noise.

Not able to keep pace with you guys but is this something that Pete has improved upon with the new designs?

Volhout
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Joined: 05/03/2018
Location: Netherlands
Posts: 4854

Posted: 02:58pm 21 Mar 2025

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PhenixRising said

Mixtel90 said Now you know why I don't design linear motor drivers, Harm. :)

It's down to the application; if running a fully loaded conveyor, continuously then, yes, efficiency becomes a consideration but there are also noise sensitive applications. For example, what messes with the ADC on the Pico? A switcher.

@Phenix,

I was under the impression that you where looking for a linear driver for a DC motor.
A DC motor uses brushes on a collector (interruptor/whatever you call them).

I think this sparking mechanical field change device creates far more noise than a PWM ever will. For sensitive applications you better use a brushless motor. Then all EMC is well defined.

Volhout

PicomiteVGA PETSCII ROBOTS

Mixtel90

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Joined: 05/10/2019
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Posted: 03:53pm 21 Mar 2025

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PhenixRising said

Mixtel90 said This is why using a linear regulator helps, there is far less supply
line noise.

Not able to keep pace with you guys but is this something that Pete has improved upon with the new designs?

Yes, his new designs are using a linear regulator for the 3V3 supply so the noise level will be lower than it is for a switcher. That should help the ADC without having to change the reference voltage to 3V.

There are disadvantages to linear regulators in some cases. The input voltage has to be greater than the output voltage plus a drop to allow for regulation. Effectively that prevents you from using even a low dropout linear regulator for 3V3 grom less than about 4V. The switcher on the Pico can work down to about 2V7 so it will even run from a couple of AA cells. The other disadvantage is efficiency. The power dropped across a linear regulator is turned to heat and lost. A switcher can be much more efficient and will often run almost cold.

Mick

Zilog Inside! nascom.info for Nascom & Gemini
Preliminary MMBasic docs & my PCB designs

PhenixRising
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Joined: 07/11/2023
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Posted: 04:32pm 21 Mar 2025

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Thanks Mick....so excited about these products

PhenixRising
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Posted: 10:53am 25 Mar 2025

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@Mixtel90

Funnily enough, Galil Motion Control, the pioneers of digital motion control, back in 1983, have just announced a new product:

Quote Galil is excited to announce the release of the new D3643 drive, which is now available for the DMC-40x0 and DMC-41x3 series of motion controllers. Based on the existing D3640 drive which is designed to run 3-phase brushless motors, the D3643 is specifically designed to run brushed motors creating a more economical solution. Both the D3643 and D3640 are linear amplifiers which means there is no switching of the power transistors. This results in smooth, ripple free motion, and high precision positioning. Linear amplifiers also generate very little electromagnetic interference (EMI).

The D3643 offers great performance for low inductance brushed motors as well as voice coil motors. The D3643 can drive 4 motors independently, at up to 1 Amp continuous and 2 Amps peak current per channel. Its voltage range is a single supply 15-40 VDC. All linear amplifiers will typically operate with far less efficiency than switching amplifiers resulting in higher heat generation. For applications requiring higher current, Galil has multiple pulse width modulation (PWM) amplifier options available. Galil can also create custom OEM solutions based on customer requirements.

They acknowledge the efficiency issue but there are cases where performance takes precedence.

Price: US$600 for four 20W amplifiers

lizby
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Joined: 17/05/2016
Location: United States
Posts: 3309

Posted: 02:25pm 25 Mar 2025

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PhenixRising said Price: US$600 for four 20W amplifiers

Probably a very reasonable price for their customers--but have you been suggesting that with CMM2 and Picomite with PIO, less than $100 is possible for the same level of control?

PicoMite, Armmite F4, SensorKits, MMBasic Hardware, Games, etc. on fruitoftheshed

PhenixRising
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Joined: 07/11/2023
Location: United Kingdom
Posts: 1139

Posted: 04:39pm 25 Mar 2025

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lizby said

PhenixRising said Price: US$600 for four 20W amplifiers

Probably a very reasonable price for their customers--but have you been suggesting that with CMM2 and Picomite with PIO, less than $100 is possible for the same level of control?

Well the $600 product above is nothing more than my schematic above but X 4. They only amplify +/- 10V motor command to drive small motors.

But in terms of motion control, Pete's 2350B DIL, equipped with DACs, line-receivers, etc., can do a better job than Galil's DMC-2143 (4-axis) motion controller @ US$1,340

The DMC-2143's on-board BASIC-like interpreter takes 500µS to process a command.

I have lots of DMC-2143's in the field but now it's gonna be PicoMites

I don't really need the CMM2 or the new HDMIUSB 2350B but I might include one as a supervisor. Still playing with ideas.

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