DC to PWM module output

Thread Starter

Hi-Tech Instruments

Joined Sep 7, 2017
20
I have a Velleman K8004 DC to PWM module kit, that I hope to use to power a tubular solenoid with 35 ohms internal resistance. I want to pulse the solenoid with a 20v, 600mA, 50℅ duty cycle, 0 to 60 Hz variable pulse, from a 30v, 1A, DC input source. The K8004 kit has a set output frequency of 100 to 5000 Hz, and the input current is only 35mA-- while I need 0 to 60Hz, and 600mA output. The kit format gives me the ability to change specific components, and I need to know which components and their values.
 

wayneh

Joined Sep 9, 2010
16,102
The K8004 kit has a set output frequency of 100 to 5000 Hz...while I need 0 to 60Hz
If you truly need 0-60Hz, I'd say you have the wrong kit and maybe the wrong idea. Zero Hz is not PWM, it's DC. You said you want 50% duty cycle with variable frequency. That also is not PWM, it's VFD (variable frequency drive).

Maybe if you provide some details about your solenoid and what you want it to do.
 

Thread Starter

Hi-Tech Instruments

Joined Sep 7, 2017
20
If you truly need 0-60Hz, I'd say you have the wrong kit and maybe the wrong idea. Zero Hz is not PWM, it's DC. You said you want 50% duty cycle with variable frequency. That also is not PWM, it's VFD (variable frequency drive).

Maybe if you provide some details about your solenoid and what you want it to do.
I am prototyping a handheld instrument based on a Ledex 3/4" x 1 1/2" pull type tubular solenoid #195204-2xx, with return spring, 35 ohms internal resistance, 20v, 600mA operating parameters. I need to be able to vary the speed of the instrument, however, 10 to 60 reciprocal plunger strokes per second (Hz) instead of 0 to 60 strokes/Hz would work fine. I need to "pulse" the solenoid, which in effect is a square wave, which is a PWM wave form. I tried a variable wave form generator, with an attached audio amplifier to boost the output. I know, for instance, that Texas Instruments has solenoid driving circuits, and I have schematics of circuits to drive inductive loads. I am not in a position to built these circuits, nor can I replicate them in the numbers I need for an initial marketing effort. Thus, the K8004 kit (or something similar) that I can tweak, replicate, package, and market. Thank you so much for your response whether we go any further or not.
 

AlbertHall

Joined Jun 4, 2014
8,184
Have you checked with Velleman that they don't mind you marketing a version of their design?
 

Thread Starter

Hi-Tech Instruments

Joined Sep 7, 2017
20
Have you checked with Velleman that they don't mind you marketing a version of their design?
It is a kit for public consumption and use. I contacted Velleman about the modifications, and they only replied that they did not offer individual modifications to their kits
 

AlbertHall

Joined Jun 4, 2014
8,184
It is a kit for public consumption and use. I contacted Velleman about the modifications, and they only replied that they did not offer individual modifications to their kits
Indeed, but you're not just going to be building a modified version, you are planning on selling copies of it. That's quite a different thing.
 

Thread Starter

Hi-Tech Instruments

Joined Sep 7, 2017
20
Indeed, but you're not just going to be building a modified version, you are planning on selling copies of it. That's quite a different thing.
I'm sorry, I thought this was a forum for discussing and developing electronics, not the legalities about the use of electronics. I would think that would be my personal concern, if, in fact, there were such issues.
 

wayneh

Joined Sep 9, 2010
16,102
I am prototyping a handheld instrument based on a Ledex 3/4" x 1 1/2" pull type tubular solenoid #195204-2xx, with return spring, 35 ohms internal resistance, 20v, 600mA operating parameters. I need to be able to vary the speed of the instrument, however, 10 to 60 reciprocal plunger strokes per second (Hz) instead of 0 to 60 strokes/Hz would work fine. I need to "pulse" the solenoid, which in effect is a square wave, which is a PWM wave form. I tried a variable wave form generator, with an attached audio amplifier to boost the output. I know, for instance, that Texas Instruments has solenoid driving circuits, and I have schematics of circuits to drive inductive loads. I am not in a position to built these circuits, nor can I replicate them in the numbers I need for an initial marketing effort. Thus, the K8004 kit (or something similar) that I can tweak, replicate, package, and market. Thank you so much for your response whether we go any further or not.
Ok, so what you really need is a variable frequency square wave in the range of 1-60Hz (or 10-60Hz) at 20V to drive an inductive load at about 600mA. This really wouldn’t be too hard to build. Are you saying you don’t want to build and prefer an off-the-shelf solution? There may be one out there but I can’t say I’ve seen one.
 

Thread Starter

Hi-Tech Instruments

Joined Sep 7, 2017
20
Ok, so what you really need is a variable frequency square wave in the range of 1-60Hz (or 10-60Hz) at 20V to drive an inductive load at about 600mA. This really wouldn’t be too hard to build. Are you saying you don’t want to build and prefer an off-the-shelf solution? There may be one out there but I can’t say I’ve seen one.
Your summary is correct. I simply do not have the wherewithal to build a module or circuit to meet my specified parameters. I have schematics for solenoid driving circuits, which I've found over the months, but they are not a viable alternative given my personal circumstances
Ok, so what you really need is a variable frequency square wave in the range of 1-60Hz (or 10-60Hz) at 20V to drive an inductive load at about 600mA. This really wouldn’t be too hard to build. Are you saying you don’t want to build and prefer an off-the-shelf solution? There may be one out there but I can’t say I’ve seen one.
Your summary is correct. I have schematics for solenoid driving circuits, Texas Instruments have them, for instance, but I do not have the wherewithal to build them. The K8004 DC to PWM module kit is the closest off-the-shelf circuit I've been able to find after months of searching, but it is only close, and I don't have the depth of knowledge to know specifically which components I need to tweak, to achieve the driving power signal I need. The K8004 is a kit, with the individual components unconnected to the circuit board, allowing me the ability to replace whatever components necessary to achieve my needs. Just Google the kit for a clearer understanding of what I'm referring to. Thanks
 

wayneh

Joined Sep 9, 2010
16,102
If you’re willing and able to build a kit, you can build your custom solution as well. But first maybe we can find something on the market. I’m hoping someone here has seen what you need, now that we understand what it is.
 

Thread Starter

Hi-Tech Instruments

Joined Sep 7, 2017
20
If you’re willing and able to build a kit, you can build your custom solution as well. But first maybe we can find something on the market. I’m hoping someone here has seen what you need, now that we understand what it is.
Wow! That sounds great! My thinking is that the K8004 kit already has all of the basic parts, like the premade circuit board, but I'm certainly open to accepting your superior knowledge and experience. I'm 70 years old and at present living in a nursing facility, but I have a soldering iron, scope/multimeter, and a few basic tool, and I am willing to pay a reasonable fee for your expertise and services, if needed.
 
When i read this thread, I keep hearing "solenoid driver", but keep seeing "voice coil driver"; but not a speaker.

Like disc drives that used a "voice coil positioner" to position the heads.

Now, like th OP, I've used the Velleman module for solenoids although my activation rate was once every 2 minutes.
I used the "soft-start" mode so the solenoid for a shutter was less violent. It was too close to a 1mm thick $800.00 USD lens.
 

Alec_t

Joined Sep 17, 2013
10,267
What is the inductance of the solenoid? Inductance results in gradual current build-up, so trying to pulse the solenoid at 60hz may cause difficulties.
 

Thread Starter

Hi-Tech Instruments

Joined Sep 7, 2017
20
What is the inductance of the solenoid? Inductance results in gradual current build-up, so trying to pulse the solenoid at 60hz may cause difficulties.
Of course, you are right, pulsing at 60 Hz may cause difficulties, but on the other hand it may not. I posted the solenoid, Testco .75 dia x 1.5 inch, pull type tubular solenoid, and the rate of pulsing the solenoid isn't my question.
 

DickCappels

Joined Aug 21, 2008
5,755
In case it is useful a link to the assembly manual for the Velleman K8004 kit, including schematic, is below.

pid_illustrated_assembly_manual_k8004.pdf


I'm sorry, I thought this was a forum for discussing and developing electronics, not the legalities about the use of electronics. I would think that would be my personal concern, if, in fact, there were such issues.
Those giving you advice may want to determine whether or not they are helping your infringe on another's rights.
 

Thread Starter

Hi-Tech Instruments

Joined Sep 7, 2017
20
In case it is useful a link to the assembly manual for the Velleman K8004 kit, including schematic, is below.

pid_illustrated_assembly_manual_k8004.pdf




Those giving you advice may want to determine whether or not they are helping your infringe on another's rights.
It is not my intention to steal and take advantage of someone else's labors, I have and plan to continue to purchase a separate K8004 kit from Velleman for each modification, not steal their schematics and build an independent module with my own parts. If I was in a position to do that I could use the many circuit schematics already available to me. At 70 years old, and in a nursing facility I am not in a position to fabricate, and perpetrate the kind of dishonest fraud you are suggesting. The K8004 kit, which I have, gives the the ability to make relatively minor modifications to achieve my power supply needs. Along with giving a common basis for evaluation and communication of what changes are needed. I have communicated directly and openly with Velleman about my needs and intentions. Thank you
 

DickCappels

Joined Aug 21, 2008
5,755
Not accusing you of anything, merely explaining why you were probably being asked those questions.

They are going to need to know the inductance. Using the information provided (Ledex #195204-2xx )I was only able to find the Ledex 195204-233 which is 83.5 ohms rather than 35 ohms.
195204-233
Would you please provide a link to the part in which you are interested or the complete part number?
 

Thread Starter

Hi-Tech Instruments

Joined Sep 7, 2017
20
Providing the inductance is less than about 100mH the solenoid should be able to operate ok at 60Hz.
www.ledex.com. STA Series Pull type tubular solenoid 3/4" dia x 1 1/2" length. I've operated the prototype with a manual contact/point configuration with no obvious problems, but I want to control my device with a digital signal. I'm sorry, but I'm just not sure how to send an attachment (data sheet), and I don't see the inductive impedance listed. Thanks so much for taking time out of your day to help me out. I've worked for months creating my prototype, but I've kind of reached my skills level with the digital power supply I need, so your assistant is greatly appreciated
 

Alec_t

Joined Sep 17, 2013
10,267
I see from the Velleman instruction manual that the K8004 kit is based on the SG3525A chip, which has a specified typical minimum oscillation frequency of 50Hz. Therefore it doesn't seem possible to modify the kit to achieve the frequency range you want :( .
 
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