Your output stage is more than adequate to drive and inductive load at 600 ma (the design max is 6 A). If it turns out that the inductance is too high for 60 Hz operation there are some tricks we can try to speed it up.

Though Alec_t's observation that the chip is designed to operate down to 100 Hz is correct, if you are not going to be in high volume production and if an occasional controller comes by that needs some special attention to get it to operate down to 10 Hz, I think it is safe to go ahead and drop the minimum oscillator frequency down to 10 Hz. In the K8004 the formula for C3, the timing capacitor is C3 =1/10 Hz x0.7 x 200,000 ohms, For 10 Hz use a 0.68 uf film capacitor.

To limit the maximum frequency to about 70 Hz (for margin) change R3 to 27k.

Is there anything besides output driver and oscillator frequency to which you think needs attention?

 

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 .

How would I be able to operate at the minimum PWM output frequency, which would be the maximum operating range of my solenoid? And what about the 600mA output current, when the input is only 35 mA?
Can I replace the basic chip?

 

How would I be able to operate at the minimum PWM output frequency

Set VR3 to its maximum.
You could try lowering the frequency further by increasing C3 (100nF in the kit) to 1uF. There is no guarantee that the chip's oscillator will work reliably, and there is a slight risk that the discharge of 1uF in each oscillator cycle, might stress the discharge transistor within the chip.

the input is only 35 mA

That is the current draw of the circuit excluding the output stage. As Dick noted, the output stage is good for more than 600mA.

Can I replace the basic chip?

I'm not aware of an alternative chip with the same pinout and general function.

 

1. Change C3 to 0.68 uf film.
2. Change R3 to 27k

 

Set VR3 to its maximum.
You could try lowering the frequency further by increasing C3 (100nF in the kit) to 1uF. There is no guarantee that the chip's oscillator will work reliably, and there is a slight risk that the discharge of 1uF in each oscillator cycle, might stress the discharge transistor within the chip.

That is the current draw of the circuit excluding the output stage. As Dick noted, the output stage is good for more than 600mA.

I'm not aware of an alternative chip with the same pinout and general function.

I will order the C3 replacement and attempt the assembly with the 1uF capacitor

1. Change C3 to 0.68 uf film.
2. Change R3 to 27k

I can't tell you how much I appreciate your assistant and input. Will give it a shot!
I also have this 12v to 40v, 10A, Pulse Width Modulator, PWM DC Motor Speed Control Switch, sold by Balance World, Inc, via Amazon. com, but this is not in a kit format. Would I be better off modifying this already assembled module, just as a prototype for demonstration purposes?

 

1. Change C3 to 0.68 uf film.
2. Change R3 to 27k

In your opinion would I be better off building a circuit, for instance based on the attached schematic?

 

I think the only way to know is to try the simpler one first. If the solenoid is not fast enough in the simplest circuit it is time to either raise the voltage or try techniques like that shown in your drawing.

As for your pre-made module in post #25, the photo does not provide much information.

For C3 it is good to avoid using an electrolytic capacitor.

 

I think the only way to know is to try the simpler one first. If the solenoid is not fast enough in the simplest circuit it is time to either raise the voltage or try techniques like that shown in your drawing.

You are obviously a good guy, and again, thanks so much for sharing your time and expertise with those of us that are struggling along in a good cause.

 

You are obviously a good guy, and again, thanks so much for sharing your time and expertise with those of us that are struggling along in a good cause.

Well, I'm out on a limb-- I've ordered a pair of DRV102 from Texas Instruments. However, I may have followed the wrong advise. The internal oscillator is monotonic at 24K

 

Sent last text too soon: set at 24Kh, PWM period. How can I get the 10 to 60 Hz I need to pulse my solenoid based device. Is there another way, a better way for me to control the speed of the solenoid. My thinking has been to change the freguency, or duration, but is there another way?
Data sheet is too big to attach

 

It should not be difficult to use. Just apply your 60 Hz and lower frequency 05% duty cycle drive pulse to pin 1. You can also adjust the effective drive voltage by varying RPWM. The driver will then output, for example, 60 Hz bursts of 24 kHz pulses, the bursts lasting 50% of the 60 Hz oscillator's period.


Below is an oscillator that can directly drive pin 1 of your DRV102 with a variable frequency 50% duty cycle pulse from its output.

Be careful to use the CMOS version of the '555 timer chip, the LMC555. The bipolar versio, NE555,n can work but it will not give you a 50% duty cycle output without adding more parts. The frequency is varied by varying Rc. The frequency, f = 1/(1.4 Rc C).

This might seem to be a step backwards because you now have a two chip solution instead of a one chip solution but now you have an oscillator designed to operate at 60 Hz and below.



Above is (vertical) oscillator frequency vs. Timing resistance (horizontal) when using a 0.1 uf capacitor. I suggest using a film capacitor.


Above is a suggested timing network for the LMC555. The frequency range will be approximately 10 Hz to 60 Hz.

 

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.

Perhaps you might read the Terms of Service you agreed to when you joined:

You agree to not use the Service to submit or link to any Content which is defamatory, abusive, hateful, threatening, spam or spam-like, likely to offend, contains adult or objectionable content, contains personal information of others, risks copyright infringement, encourages unlawful activity, or otherwise violates any laws.

 

It should not be difficult to use. Just apply your 60 Hz and lower frequency 05% duty cycle drive pulse to pin 1. You can also adjust the effective drive voltage by varying RPWM. The driver will then output, for example, 60 Hz bursts of 24 kHz pulses, the bursts lasting 50% of the 60 Hz oscillator's period.

View attachment 135698
Below is an oscillator that can directly drive pin 1 of your DRV102 with a variable frequency 50% duty cycle pulse from its output.
View attachment 135699
Be careful to use the CMOS version of the '555 timer chip, the LMC555. The bipolar versio, NE555,n can work but it will not give you a 50% duty cycle output without adding more parts. The frequency is varied by varying Rc. The frequency, f = 1/(1.4 Rc C).

This might seem to be a step backwards because you now have a two chip solution instead of a one chip solution but now you have an oscillator designed to operate at 60 Hz and below.

View attachment 135702

Above is (vertical) oscillator frequency vs. Timing resistance (horizontal) when using a 0.1 uf capacitor. I suggest using a film capacitor.

View attachment 135701
Above is a suggested timing network for the LMC555. The frequency range will be approximately 10 Hz to 60 Hz.

 

Mr Cappels, thank you for keeping my hope alive in getting this challenge worked out. I will order the LMC555, and you said I need to vary Rc. Am I correct in believing that the second circuit I need to attach to DRV102, which represents the variable Rc and capacitor arrangement to adjust the frequency range? Sorry if I am being obtuse, but I'm just trying to be sure I understand what you telling me. Again, thank you so much.
][/QUOTE]

 

Texas Instruments offers a LMC555CM, while you indicated LMC555COMS; is the LMC555CM the correct one?

 

LMC555 will work: http://www.ti.com/lit/ds/symlink/lmc555.pdf

The automotive qualified tic555 should also work http://www.ti.com/lit/ds/symlink/tlc555-q1.pdf

I also want to offer a very weird CSS555 timer: http://www.customsiliconsolutions.com/products-for-ASIC-solutions/standard-IC-products.aspx
It CAN be programmed. i.e. with a PC

 

LMC555 will work: http://www.ti.com/lit/ds/symlink/lmc555.pdf

The automotive qualified tic555 should also work http://www.ti.com/lit/ds/symlink/tlc555-q1.pdf

I also want to offer a very weird CSS555 timer: http://www.customsiliconsolutions.com/products-for-ASIC-solutions/standard-IC-products.aspx
It CAN be programmed. i.e. with a PC

Thanks, but I don't have a PC!

 

I downloaded the LMC555 COMS data sheet, thank you. I'm in a little over my pay grade, but I'm going to attempt to lay the whole schematic out: the LMC555; DRV102; and the variable timing circuit--attachment 135701. Of course I hope that will give me a better understanding of what I'm actually trying to achieve, and allow me to put together a comprehensive parts list so I can order everything I need.
My situation, physically and financially, are both an added challenge--70 a few days ago, in a nursing facility, and just had major neck surgery 10 days ago.
Not complaining, just have some extra hurtles to get over, which is why I am so appreciative of the assistance you guys are so unselfishly willing to give me.
I truly have a prototype of an instrument already done that has the potential to change a well established industry. Hope to share it with you