I would recommend working on your schematic, get a breadboard (if you don't have one), get a bill of materials (BOM), and then ordering from a reliable source, e.g., Farnell in the UK. You may actually find that is cheaper than eBay. I would use current devices, as they are often much cheaper, replaceable, and may be better.

Electronics, unlike wine, don't get better with age.

BTW, on a personal note, my home is in the middle of a large area of state-owned woods. One of the things I enjoy most is watching the variety of birds we have. There is a mixture of aquatic and land birds. I have seen storks and cranes (a have a small pond). There are of course hawks, turkey buzzards (and turkeys), a falcon, and so forth. In June, I saw a Bald Eagle not more than a mile from my property. It was feeding on road kill. Later, I saw a juvenile raptor on top my flag pole, but I couldn't identify it. A couple of days ago, I saw it again, and thought it might be a Golden Eagle. It was looking interested in a small ground hog near the base. My brother suggested it might still be a young Bald Eagle. Apparently, they are hard to tell apart as juveniles. Raptoring is out of my league, but I think it would be fun.

Edit: I just noticed your location as West Midlands. I don't know anything about your area, but I recall there is an active model soaring club there. You may want to take a look at their launch winches.

John

 

BTW, on a personal note, my home is in the middle of a large area of state-owned woods. There are of course hawks, turkey buzzards (and turkeys), a falcon, and so forth. In June, I saw a Bald Eagle not more than a mile from my property.
John

We get wide variety of raptors, but this summer we had a couple of rare visitors in the city, two Mississippi Kites, rare visitors and a long way from home.
Max.

 

For a tried & true PWM ckt, check Bill's Blog, LEDs, 555s , flashers---, Fig 5.2, # 1. For motors I use a clock around 2 kHz.

 

Will the noise affect the raptors? I didn't mention it, but for the device examples I showed, I was above 20 KHz. I don't know the upper limit of raptors.

John

 

For motors I use a clock around 2 kHz.

I used the PICmicro suggested 4Khz minimum this is the MIN level they claim creates imperceptible (to humans) Motor noise.
Max.

 

Hi all,

I got probably all of the parts here except the two chips we are looking at and the Mosfet's, I used to work in this industry until 7 years ago when work was getting harder to come by, I was mainly R & D so we just got a basic schematic and built the prototype then tweaked the design to ensure it fully worked before completing the Schematic and moving onto board layout...

All of my gear is boxed up here in the house in what was my office, now junk/storage room... I know exactly where my Tektronix portable digital scope is as it took me a long time to save up to buy her...

I actually fly one of your more common birds, a Male Harris Hawk got mates that fly the Red Tailed Hawk, as both species are very common falconry birds here in the UK...

Been looking last night at the data sheet for the LM3524, can we actually use a pot on it to vary the PWM output? as the only time it shows a pot on any of there drawings is when they actually test the chip... no mention of it in any of it any where else...

By the way, not sure if my Schematic/Board Layout software still works as I was using Ulticap and Ultiboard way before they moved over and got incorporated into Electronics Workbench, after that point all my old libraries and previous drawings were unreadable, un viewable in the newer versions so had to keep a copy of the software running for some of my clients but as most if not all are no longer trading I don't have any need to keep an eye on it, it's on the old works computer will have to power her up and see...

Failing that will have to do a internet search for some software, must be something free out there I can use... I actually started off using Vutrax many moons ago...

 

Noise will be an issue, but not in the sense you are thinking...

Eventually the bird will clock onto what we are doing, by either seeing the setup (not properly hidden) or by watching me do something prior to it firing up, once they have worked out it's not actually a bunny they are chasing may refuse to chase it, that's when the fun starts...

So the noise of the motor it's self could cause us a problem, but if it helps train the birds initially starting out then it's all been worth it...

Will not be just a straight line run, will have to have it running round tree's etc just like a rabbit would...

At least this is more human than the much older methods used...

 

Re: LM3524

Pin 16 provides a reference voltage of 5V. That is often used with a potentiometer to ground. The wiper is fed to pin 2 to give variable control, See these examples:

http://www.camotruck.net/rollins/lm3524-motor.html (first image)
http://www.ti.com/lit/an/snoa625b/snoa625b.pdf (Figure 1)

John

 

Thank you John, just ordered two of them so that I can start looking at that side of the design tonight whilst I await delivery of them...

Just did not wish to mess about programming a pic, don't think this project warrants it...

 

How do I work out the ideal pwm for the motor as I need max speed and a slow speed so what is the best way of doing this or will it be more trial and error?

 

There are two terms used with PWM that may have confused you. The first is the "Duty Cycle", which is is the ratio of the high (power) pulse duration to the total duration of the cycle. It is usually expressed as a percentage. Thus, 100% Duty Cycle means the motor is getting pure DC current and will provide its maximum power. 0% means there is no power. Motors require a certain amount of power in excess of 0% just to turn. Your motor may barely turn at 5%; others may require 10%.

So, your maximum power/speed will be at 100% duty cycle; your minimum will depend n the motor, but will be some percentage that is less than 100%. I am just guessing, but suspect that the lowest usable speed will be observed at 20% to 30% duty cycle.

The second term is frequency of the PWM. We discussed it briefly above. Some people prefer a low frequency, say 1200 to 2400 Hz. Other's use a much higher frequency, say 20 KHz. And others used a frequency that is in between. A lot has been written about the "best" frequency. Part of the problem is defining "best." At low frequencies, one gets audible noise from the motor windings. Sometimes, that property is used on purpose to provide programming clues while programming the controller. I find the noise annoying, so used a higher frequency that did not produce it. Another factor to consider in choosing the frequency is switching loss. Each time the PWM current switches (i.e., mosfets) switch on or off, there is a small period of transition and generation of heat. Low frequencies minimize the number of transitions and are potentially more efficient on that basis. Probably more important than efficiency per se inyour application is the heat generated. So, choice of frequency must balance at least those two considerations. MaxHeadRoom mentioned a recommendation of 4000 Hz. 4QD (a UK controller manufacturer) used to favor a higher frequency. I suggest doing some reading on the subject. Or, start at 4000 Hz and make your design flexible enough to increase the frequency should the squeal bother you. At my age, I don't think I can hear much about 3500 Hz. I don't know anything about the hearing of your birds. I suspect it goes to pretty high frequencies.

John

 

Birds are most sensitive to sounds with frequencies between 1 and 5 kHz. The upper limit of hearing is about 10 kHz (Brooke and Birkhead, 1991). Humans can hear sounds with frequencies as low as 0.02 kHz and as high as 17 kHz.

Brooke, Michael and Tim Birkhead, ed. The Cambridge Encyclopedia of Ornithology. Cambridge: Cambridge University Press, 1991.

http://seaworld.org/animal-info/animal-infobooks/raptors/senses/

So that has solved that question... we need to keep away from the 1 and 5 kHz range... should not cause too much of a problem, it's not like they are going to be subjected to it for hours at a time, were talking minutes if not seconds...

Therefore I believe I should be ok running it at 20Khz...

I know the basics of PWM but it's been awhile, I used to only be worried about the mark to space ratio, usually for working out Baud Rate, when using serial comms, as that was the first task when ever we did any programming, that way we could send out ascii characters to hyper terminal to help debug the code we were working on...

I have just purchased a single channel wireless remote to add into the circuit...

http://www.ebay.co.uk/itm/251352801...49&var=550289505886&ssPageName=STRK:MEBIDX:IT

Hopefully this way we can trigger the lure without the bird realising what we are doing, I decided to buy this bit purpose built to save time and effort on the build... I have done remote controls using a pic before as it had the encryption built in to auto scramble code on every push to ensure against someone grabbing the code...

So I am slowly with your wealth of knowledge and support getting the project slowly to take shape and understand basically what we are trying to achieve... I'm concerned about how much knowledge I have forgotten, in just a short space of time... I seem to be coming over as a newbie, so I had better buck up my idea's... lol

For the MOSFET Driver, am I just looking for something that can control a half bridge or is there more involved than just that?

http://www.irf.com/product-info/datasheets/data/ir21531.pdf

http://www.irf.com/product-info/datasheets/data/ir2103.pdf

Would they be suitable?

Or do I need to factor in the PWM?

As they would not be handling any load would they, as the FET's would be doing that side on things, but I need half bridge to control multiple FET's or have I got things backwards...

As for the actual MOSFET what actually am I looking for, especially if we are going to cascade them?

 

The IR 21531 does not appear to allow PWM. It does allow frequency control. The IR2103 may not inherently allow PWM either; although, I did not read its datasheet that carefully. It does have inputs for the high side and low side.

Here is a link to the archive page of 4QD. There is a wealth of information there on motor control.

http://www.4qdtec.com/

John

 

Thank you, so I am searching for one with Half Bridge and PWM control...

So not all mosfet drivers have PWM control, ooops I took that as industry standard...

Will study your link, thank you

 

Half Bridge driver IR2110?
Max.

 

Cannot see where it states it's PWM...

http://www.irf.com/product-info/datasheets/data/ir2110.pdf

Must have lost the knack of reading data sheets...

 

Cannot see where it states it's PWM...

..

The IR1220 was designed for it!
Doesn't generate PWM however.
Max.

 

I have used the IR2110 and some others in that series. What I liked about the LT1158 was the single input:


There are several other devices that are also are single input. I used this search term: mosfet half-bridge single-input driver

That might be advantageous (fewer parts) if one uses a simple 555-based oscillator or Schmitt-inverter oscillator to generate the PWM. Since the latter often comes in a single package with 2 to 6 gates, those additional gates may have other uses for the enhancements Icarus has mentioned.

I don't think the oscillator will make much difference, so long as it is PWM'd, unless you want soft-start as I did in my application.

John

 

The reason I am looking for something other than the LT1158, is that of availability in the UK, there does not seem to be many about, most are being imported or sent from America...

Also the price of it is treble that of other types...

The datasheet and application notes for the LM3524 are very poorly written, I am struggling to work out how to set it up correctly...

Will post shortly what I have found...

 

So the oscillator is set by an external resistor RT and capacitor CT,

The recommended values of RT are 1.8K to 100K and CT are 0.001uF to 0.1uF​

​

are we using the formula F= 1/2 Pi RC​

​

if so how do I re-work it for a 20KHz​