Darlington Power Pack
NWCCTV
Posts: 3,629
So in my latest Garage sale deals I acquired a few of these http://www.ebay.com/itm/STK-0070-Darlington-Power-Pack-Integrated-Circuit-x-22-pieces-/290781158178?pt=LH_DefaultDomain_0&hash=item43b3e85b22
along with severl other power amps, etc similar to this. Can anyone tell me what they are or possibly could be used for?
along with severl other power amps, etc similar to this. Can anyone tell me what they are or possibly could be used for?
Comments
Your biggest issues with development of them as h-bridges is how many watts they will drive (audio amps usually will take a range of voltages) and how much of a voltage drop the h-bridges will create. You have to provide a power supply with a voltage that provides for the motor and above that for the voltage drops.
And at the other end, you need to get your ducks in a row as to how the input is going to handle a digital PWM signal. That may be very easy as most power ends of audio expect a pre-amp to provide a signal of some significance. They are just the final power output stage.
Still, after you get all that done to create an h-bridge, I'd prefer Bob Blick's Darlington h-bridge design as it is much more straight forward. It is for 5amps, about 100watts output, but one could change the Darlingtons to get even more. Besides, the seller wants $374 total for 22 items (over $15 per unit) and the TIP120s and TIP125s will cost you about $3 USD total for one h-bridge.
http://www.bobblick.com/techref/projects/hbridge/hbridge.html
Methinks you might be shopping EBay too much unless this is just reference material.
If it is support for a good audio project you want go here.
http://sound.westhost.com/
And if you are going to sell them to somebody that needs to build a 43 to 55 volt audio power supply for them, you are going to need the above link any way. They seem to be 70watt single amps in a chip of two matching PNP and NPN Darlington arrays. The power supply is going to cost far more than the chip -- transformers, big capacitors, huge rectifiers, cooling, etc.
I hope you paid far less than what the EBay site is asking.
If you want to get good yard sale deals you have to do two things.
1. Show up at 6am, those that are first have more to choose from.
2. Limit yourself to paying 1/20th of what you think it is worth. This limit will allow you to always get your cash back on mistakes.
They are interesting devices. It is just that solid-state audio has been changing very rapidly. Since some are mono amp chips, guitar amps and PA are appealing uses. There may be someone that need them for repair of such.
THD is the figure that audiophiles are very concerned about. It doesn't matter for h-bridges and digital control.
And the STK0070 is a 70 watt, 7 amp rated device. That compares to a TIP131/TIP136 pair which Futurelec sells for 90 cents and 75 cents respectively. But the TIPs will handle more voltage, up to 80 V.
70 watts through one speaker is LOUD. The average room requires only about 10-15 watts.
On the other hand, 70 watts is less than 1/10th a horsepower for a motor. And because they are Darlington arrays, you just might be able to drive them directly from 5 volt logic with a 220 current limiting resistor. But I suspect the voltage drop in high power use could total nearly 8 volts. In other words, a 24 VDC motor would require a 32 volt supply; a 12VDC motor would require a 20VDC supply and at 7 amps.
But you might have to use a 2n2222 for a front end at there is something about requiring 40 to 70 ma to drive the Darlington. That is above the 20-25ma limit of a microprocessor. (These are just repackaged BJTs with a few resistors and maybe some diodes.)
I don't think these will work well as h-bridges - too many added features to improve audio, maybe Class A amps.
http://www.bdent.com/v/vspfiles/downloadables/STK0070.pdf
Depends on what you are doing with the H bridge. Not much good for PWM, switching speed/slew rate is too low, but if you only need to drive a motor forward or reverse they are ok. Can also be used to vary the voltage on the motor.
I actually like them as audio output. They may sound good and work quite well. But 7 amp per channel 48VDC transformers are going to put a big dent in one's pocket.
6:00 AM????? I am lucky if I am up by 11:00 AM. I am and most always have been a night person. It helps me get remote work done for my clients while they are in bed!!!!! These last few finds have just been luck. This hasd been a good summer for sales for both the wife and I. We normally go out every other weekend or so, sometimes every week if there are a lot. Estate sales are best. For my last 3 killer finds I got them near the end of the day on Sunday. People just want to get rid of things rather than packing them up. Apparently no one before me liked to dig through the boxes to see what was there. In this last find the first thing that struck me was an IR transmitter brand new in a box. I figured if there was one there would be more but I was wrong. However, I still have a boat load of items to go through. Most are various diodes and transisistors. I did find a 5 MHz Crystal that I can use. Once I sort everything out I will start another thread in the Classified section with a list of all items.
That said, with everything else I have going on it would not be wise to take on more projets. So, If anyone wants any of these current items just PM me and will see what we can work out. I am in to pretty much anything Parallax and also CCTV items such as board cameras, etc. It may take me a few days to get a list together with everything else on it. I am sure rwgast_logicdesign will attest that I am pretty fair with my trades!!!!
Edit: I forgot to say Thank you Loopy for the PDF file. I am sure it will be of use to myself or anyone else that may want some of these.
As far as the 5mhz xtal if you want to use that with your prop set up you need to make sure its a 2 pin 20pf or 18pf.
OK, I will double check that. Even still, I can find other uses for it. Thanks for the comment!!