Search found 39 matches
- Sat Mar 07, 2009 11:37 pm
- Forum: General Discussion
- Topic: Help With Spec Sheet: MM74C926
- Replies: 20
- Views: 11576
Re: Help With Spec Sheet: MM74C926
OK, you come out serial and then what? Feed the serial data to an SR and latch the parallel data into the LEDs. Simple, really. So the serial data would be in seven segment code at the uc output? Do you know of some real cheap LED display (four digit at least and nice BIG numbers like 1/2 inch) tha...
- Sat Mar 07, 2009 11:25 pm
- Forum: General Discussion
- Topic: Help With Spec Sheet: MM74C926
- Replies: 20
- Views: 11576
Re: Help With Spec Sheet: MM74C926
I said "rotary". I meant thumwheel switch. About $5 and it is the only component you need. Seems to make sense to me. Okay. But why the red ink?... Quotes within quotes within quotes. I thought the red color would make it easier to read: easier to tell what I was saying in the latest repl...
- Thu Mar 05, 2009 7:44 am
- Forum: General Discussion
- Topic: Help With Spec Sheet: MM74C926
- Replies: 20
- Views: 11576
Re: Help With Spec Sheet: MM74C926
A BCD rotary switch should provide the range selection I need with only two or at most three INs. BCD? Why? Wouldn't a rotary digital pot and human feedback from the existing readout LCD/LED suffice? Turn pot up or down, fix value by hitting 'enter' button adjacent to the pot. Or, use a digital enc...
- Tue Mar 03, 2009 10:31 pm
- Forum: General Discussion
- Topic: Help With Spec Sheet: MM74C926
- Replies: 20
- Views: 11576
Re: Help With Spec Sheet: MM74C926
Thanks guys for starting the thought process. I made a parts list for my original tach circuit and priced it today and was surprised to find that my cheap solution was not that cheap. It came to about $40. I was hoping for $20 or less. So I started to sketch a generic circuit with a uC and was again...
- Sun Mar 01, 2009 11:08 pm
- Forum: General Discussion
- Topic: Help With Spec Sheet: MM74C926
- Replies: 20
- Views: 11576
Re: Help With Spec Sheet: MM74C926
My overall project is a manual controller for two or perhaps three stepper motors that will automate a small milling machine. It will have provision for future computer control, but for now, I want to get the manual control working well first. The tach circuit will be to display the speed of the mov...
- Sat Feb 28, 2009 3:50 pm
- Forum: General Discussion
- Topic: quick logic level question
- Replies: 7
- Views: 3393
Re: quick logic level question
The best answer to this may depend on what you are doing with the signal after "converting" it. If you are going into a 3.3 Volt logic chip, a resistor dividing network may work just fine. As a further precaution you may want to add a diode between the 3.3 Volt input and the 3.3Volt supply...
- Sat Feb 28, 2009 3:33 pm
- Forum: General Discussion
- Topic: Help With Spec Sheet: MM74C926
- Replies: 20
- Views: 11576
Re: Help With Spec Sheet: MM74C926
If you have a better way to make a quick and dirty counter, I am all ears. The simple answer is to add a microcontroller (uC) to your project. Costs about one eighth of the MM74C926, based on Digikey pricing. I have been experimenting with some uCs and I did think of that. But then you have to inte...
- Fri Feb 27, 2009 11:46 pm
- Forum: Robotics
- Topic: stepper motor Help
- Replies: 1
- Views: 4382
Re: stepper motor Help
Steppers are generally one of two types: unipolar and bipolar. The unipolar will usually have six wires. They will be connected to two center tapped coils and should have enough resistance to allow figuring them out with a regular Ohm meter. Each end to the center tap will have the same resistance a...
- Fri Feb 27, 2009 11:19 pm
- Forum: General Discussion
- Topic: Help With Spec Sheet: MM74C926
- Replies: 20
- Views: 11576
Re: Help With Spec Sheet: MM74C926
Thanks! Yes, it is a bit old, but still available. So is the 741 which is a lot older: at least 40 years and that is a lot before Reagan was in the White House.
If you have a better way to make a quick and dirty counter, I am all ears.
If you have a better way to make a quick and dirty counter, I am all ears.
- Fri Feb 27, 2009 6:16 pm
- Forum: General Discussion
- Topic: Mass wire storage solutions
- Replies: 11
- Views: 6276
Re: Mass wire storage solutions
I have a similar problem at work. I use cardboard bins and inexpensive (not cheap) metal shelves. The bins are available in a variety of widths and are relatively inexpensive. I have some cardboard bins that are over 25 years old do they do last. They have nice white areas on the front for labels an...
- Fri Feb 27, 2009 6:06 pm
- Forum: General Discussion
- Topic: Help With Spec Sheet: MM74C926
- Replies: 20
- Views: 11576
Help With Spec Sheet: MM74C926
I am looking at using a Fairchild MM74C926 to implement a counter circuit for use as a tach. for a stepper motor. The Fairchild spec sheet shows a number of waveform times for operating the IC, but the thing I am confused about is that all the minimum values are larger than the typical values. The m...
- Tue Oct 11, 2005 12:41 pm
- Forum: General Discussion
- Topic: I am claiming dunce of the week
- Replies: 44
- Views: 19471
Re: I am claiming dunce of the week
jwax said,<p>"I was USAF, repairing shot up planes in Vietnam, when (I hear it happens to everybody-once!) after soldering 128 wires on the back of a big ass Cannon connector, discover I forgot to put the locking ring over the wires before soldering. De-solder 128 wires, curse, add ring, solder...
- Fri Oct 07, 2005 11:09 am
- Forum: General Discussion
- Topic: AC line / UPS power switch
- Replies: 15
- Views: 6156
Re: AC line / UPS power switch
It wouldn't be hard to make such a switch. Buy a couple of extension cords, a three way switch, and a small box to put it in. There are plastic boxes available in hardware stores that would look OK on or under the table. For table top use you can cut any mounting ears off. Be sure to get the three c...
- Fri Sep 30, 2005 7:15 pm
- Forum: General Discussion
- Topic: electric motor question
- Replies: 12
- Views: 4875
Re: electric motor question
Slow down. You really should not have to rewire the garage. <p>Any motor that is designed for dual voltage operation simply has windings that are wound in two sections. Each section needs 115 Volts. When they are in series, the line Voltage is 230. When they are in parallel, it is 115. In either cas...
- Fri Sep 30, 2005 6:57 pm
- Forum: General Discussion
- Topic: Variable PS Design
- Replies: 16
- Views: 6867
Re: Variable PS Design
Thanks guys! <p>RE: Linear vs Switcher. Yes, I know from experience. 33V (you need a little headroom) - 0.001V times 3 Amps = 100 Watts. That's a small room heater. If you do the research on heat sinks, you find that a switcher is real attractive. I'm not committed to it, but it is most likely a nec...