I have situation where I need to use darlington transistor array to connect electromagnet to VCC. Normally PNP transistors are used for that, but I don't see any arrays for those. Can HEX inverter be used along with with NPN array to accomplish that?
Connect the electromagnet coil to VCC, not ground. Then you can use NPN directly.
aarg:
Connect the electromagnet coil to VCC, not ground. Then you can use NPN directly.
Yes, but I actually need to have it connected to either GND or VCC in order reverse magnetic field.
Like in the photo above which is basically H-Bridge. But I want to use transistor arrays instead (there's A LOT of coils). So T1 and T2 are ok, but but I want to use NPNs instead of Q1 and Q2 possibly with hex inverter. Would that work?
... also there are some powerful drivers available. In this list, check out the ULN2003V. Only $0.54 and 7 channels, 100mA source, 140mA sink per channel. No transistors required.
Mosfets are more "normal" for this application than PNP's, since the price dropped about 20 years ago.
Try looking at parts like these to reduce the number of components needed.
Fancier parts will give you more help on the control lines so turning on P1G and N1G at the same time for example won't be as likely and the part will not be damaged (avoiding "shoot-thru").
You will see it has P-channel MOSFETs for the upper parts and N-channel MOSFETs for the lower parts.
Thanks! I didnt know about this part. Its an H bridge but so inexpnsive, wow!
Well, how much are 4 discrete transistors and your time to wire them all up?
Or, PNP "array" (4 PNPs in a common package)
The MOSFETs will need a lot less control current (next to none) while the PNP will need a lot more and may not be able to support the current needed for your inductor.
dlloyd:
... also there are some powerful drivers available. In this list, check out the ULN2003V. Only $0.54 and 7 channels, 100mA source, 140mA sink per channel. No transistors required.
I don't think these can source current. At least not according to DatSheet if I'm not mistaken. I was planning to use ULN2003 arrays in this project as alternative to H-bridges.
aarg:
Mosfets are more "normal" for this application than PNP's, since the price dropped about 20 years ago.
Are you saying that NPN Mosfets can source current? I tried a little experiment with TIP-120 (I know it's not a MOSFET) and LED. Sinking current was no problem but when I connected it to source current, LED would light up but very dimly...
CrossRoads:
Here's a simple H-bridge matrix that can be expanded to more coils.
Thanks CrossRoads! That makes sense. Here's my schematic with transistors which I know can be replaced with H-bridges.
I wanted to use arrays instead of H-bridges because of the cost mostly. H-bridge that that I was originally planning to source (L293D) costs $3.32. And I'll need 6 of them ($19.92).
While 7 channel ULN2003 is only $0.42, and I'd only need 2 of them ($0.84). Plus 2 Hex inverters (if I indeed can use them)...
We still have no specs for your solenoids - what voltage and current?
You have no free wheel diodes anywhere so you seem to be on your way to
burning lots of transistors up.
MarkT:
We still have no specs for your solenoids - what voltage and current?You have no free wheel diodes anywhere so you seem to be on your way to
burning lots of transistors up.
They work anywhere from 5 to 24 V (I plan to use 12V) , and less than 20mA current.
Good point about diodes. I didn't include them in schematic for simplicity. But ULN2003 arrays already have diodes as well as H-bridges...
Also these are for split-dot displays... About 10ms pulse is sufficient to flip dot.
No, try again. datasheet, partnumber, actual information, not 2nd-hand description.
ULN2003 is not going to source current (how can it? all the emitters are connected together internally), that's going to need PNP or P-channel MOSFET or an array wth discrete outputs.
You'd only need 6 of the chips I mentioned back in reply #5, a whopping $4.25 total.
MarkT:
No, try again. datasheet, partnumber, actual information, not 2nd-hand description.
2nd hand description is all I have. These were made 30 years ago, no documentation exists or can be found.
And my original question was actually about using hex inverts with NPN transistors.
CrossRoads:
ULN2003 is not going to source current (how can it? all the emitters are connected together internally), that's going to need PNP or P-channel MOSFET or an array wth discrete outputs.
You'd only need 6 of the chips I mentioned back in reply #5, a whopping $4.25 total.
Thanks CrossRoads. I saw that, just didn't see DIP version (so can test it on breadboard)...
But putting this project and costs aside, just for my own education, can Hex Inverter be used with ULN2003 to source current? 
Then measure the voltage they are operated at and the coil resistance.
MarkT:
Then measure the voltage they are operated at and the coil resistance.
I'll measure it tonight. But what for? To find out current?
When you say hex inverters, what particular part are you suggesting?
Yes, you can use that.
Between its voltage drop across the output and the ULN2003/2803 voltage drop, you lose a lot of volts to develop any current thru your inductors.
CrossRoads:
When you say hex inverters, what particular part are you suggesting?
Yes, you can use that.
MIC2981/82YN Microchip Technology | Integrated Circuits (ICs) | DigiKey
Between its voltage drop across the output and the ULN2003/2803 voltage drop, you lose a lot of volts to develop any current thru your inductors.
Thanks so much for the info! Didn't realize about voltage drop, I guess it's not a good idea then
I was thinking about SN7406, just realized I didn't post that information in the beginning my bad!
As always I really appreciate all the information I got here! I think I have sufficient data to build a driver for my flip dot display
CrossRoads, special thanks for DMHC3025LSD part recommendation! That's fantastic little chip, I'm going to order a bunch today!
I also found this crazy 12 channel mosfet "TC7320" made by MicroChip, but looks like it's not sold anywhere 
Too high anyway:
Rds On - Drain-Source Resistance:
20 Ohms