Need help with 555 timer circuit

[robertgzzzt]

No, Kris......it's fine. I went ahead and ordered five of the NTD4906s from Digi-Key, along with some 8 and 16 pin DIP sockets that I needed. I assumed you knew what you were doing when you selected it. Thank you so very much for all of your help.......and you too Steve

 

[robertgzzzt]

I hate to pester you guys again, but another little issue has cropped up. I built my 10 LED chaser circuit on the breadboard that I'll be using, via with some .5mm fiber optic strands, in the floor of the shuttle bay, to create a runway lights effect. I also just successfully built the aforementioned blinker circuit on a piece of veroboard. It's only driving a single LED at the moment, until the MOSFET arrives. Anyway, I have the wall wart connected to the stripboard, and the LED is flashing at it's designed rate, until I hooked up the chaser circuit from the breadboard, then my blinker LED started flashing faster. When I disconnect the breadboard, the flashing rate on the blinker circuit returns to normal.

I'm also going to have a strobe circuit running off of a separate 555 timer, driving 5 white LEDs, and a "fader" circuit, at the push of a button, ramps up in amber, then a second push of a button, fades out and ramps up in blue (this one I'm going to have to purchase, I can't find a schematic anywhere). Aside from those circuits, there will also be a bunch of static LEDs lighting windows throughout the model. How I can prevent all these circuits from interfering with one another?

 

[(*steve*)]

The chaser circuit may be putting spikes on the power supply.

Do you have a capacitor between pin 5 of the 555 and ground?

 

[robertgzzzt]

The chaser circuit may be putting spikes on the power supply.

Do you have a capacitor between pin 5 of the 555 and ground?

Sorry it took so long to get back. To answer your question, no, actually, I didn't. The schematic for the chaser circuit did actually call for a .01uF cap between pin 5 and GND. I don't have one that small. The closest thing I have is .1uF. I tried it (on the chaser circuit) and it didn't help.

The chaser circuit also utilizes a 555 timer, was that the "pin 5" you were referring to? Should I install a .01uF CAP on the control pin of ALL the 555 timer circuits?

 

[(*steve*)]

Use the 0.1uF and see how you go. It's not that critical.

I would tend to use it always as it's cheap insurance.

 

[robertgzzzt]

Works like a champ, brotha. Thanks again

 

[robertgzzzt]

The MOSFETS came in yesterday evening. These things are very tiny, but the short, flat pins are too large to fit through the holes in the Veroboard. The pin spacing is fine, but as short as they are, I'm kinda worried about the MOSFET getting too hot while I'm soldering it. I'll need to apply the heat for about three seconds, maybe four. I obviously don't want to damage the component. Should I use something like this, or do you think I'll be ok without it??..... http://www.digikey.com/product-detail/en/382437-1/A26245-ND/333070 . I have a small enough drill bit to ream the holes out enough to get the pins to pass through.

 

[KrisBlueNZ]

Hmm. Thanks for the feedback. I'll have to reconsider my recommendation for that device, if it's going to prove difficult to work with.

I wouldn't worry about overheating the device. If you're worried, you could solder it like this: 1. Stick the leads through the stripboard. 2. Tin a lead, close to the copper. 3. Tin the stripboard on both sides of the hole. 4. Heat the lead and the stripboard together and apply solder. 5. Wait 5~10 seconds before moving on to the next lead.

That should limit the total application of heat to less than two seconds per instance.

You might prefer to mount it flat onto the copper side, for rigidity. That would be guaranteed to heat it up more, but still very unlikely to damage it.

Please let me know how you get on.

 

[robertgzzzt]

Actually, upon closer inspection, it was the pin spacing that was the problem, not the pin size. I was able to spread the pins out with my fingernail, and line them up enough to pass through the holes, but it wouldn't press all the way down onto the board, which in this situation is a good thing. The plastic housing is standing off about 1mm, no big deal.

I think by the time I do all that tinning I can have it soldered. I see what you're saying though, spread the work out, but once my solder starts to melt, it goes very rapidly from there, in other words, if I'm going to tin, I might as well just go for it. I've learned that tinning my tip before I touch the work makes for a much better solder joint and the heat transfers much faster. Thanks again, Kris.

 

[KrisBlueNZ]

Actually, upon closer inspection, it was the pin spacing that was the problem, not the pin size. I was able to spread the pins out with my fingernail, and line them up enough to pass through the holes, but it wouldn't press all the way down onto the board, which in this situation is a good thing. The plastic housing is standing off about 1mm, no big deal.

Right, that sounds good.

I think by the time I do all that tinning I can have it soldered. I see what you're saying though, spread the work out, but once my solder starts to melt, it goes very rapidly from there, in other words, if I'm going to tin, I might as well just go for it.

Right. I very much doubt you'll do any harm to the device.

I've learned that tinning my tip before I touch the work makes for a much better solder joint and the heat transfers much faster. Thanks again, Kris.

Yes, that's very important. You should have a slightly damp sponge to wipe the tip on. Saturate the sponge then squeeze the water out of it. Wipe the tip completely clean then re-tin it immediately.

 

[robertgzzzt]

I hope to build these circuits using a PIC one of these days, if I can learn hot air soldering and how to program the chips. How hard can it be to program a chip to go output high for 1 second, output low for 1 second? It's a rhetorical question, unless you want to answer

 

[robertgzzzt]

I just thought you guys might like an update. I've hooked everything up for a test run, and my 10 LEDs have been blinking for about an hour now. All the components are cool to the touch, even the power supply. The LEDs are now ready for installation inside the model when I get to that point. Thanks again, fellas. I really appreciate all the help.

 

[(*steve*)]

How hard can it be to program a chip to go output high for 1 second, output low for 1 second?

You'll find that this is pretty much the first program you write on *any* microcontroller.

In fact, even if I don't need one, I make sure there's a LED attached to a pin of a microcontroller in every project I make. That way I can initially program a LED flasher for a very simple test of the circuit.

A LED is almost as important as the programming interface

It's a rhetorical question, unless you want to answer

Sorry, pretend I didn't answer

 

[robertgzzzt]

Greetings gentlemen,

I have to put my PIC programming on hold for now, but i have all the information and articles bookmarked and my hardware in a wishlist.....

I've been working on this Enterprise model and I'm trying to plan out how I'm going to run wires from all the LEDs to the PCBs and switches that will be mounted in the display base. I've figured it up and there will be approximately 60 LEDs in this model, some of the LEDs will actually be short lengths of LED strip tape, for which I'm counting as a single LED.

What I'm trying to figure out is a clean, neat way of bring several wires, leads and grounds, together into one single positive and negative wire. I thought of using **this** and soldering it onto a piece of stripboard, then connect all the positive and negative rails together to a single positive and negative input wire, then solder the wires from the LEDs to the **female version** , or just solder them directly to the male header.

I'm using 30awg magnet wire on my LEDs (because it's very small and easy to work with in tight spaces) and I'll probably want to use 22awg hookup wire on the other side of the junction. Essentially I'm wanting to turn a bunch of 30awg + and - magnet wires into a single + and - hookup wire. It might be 8 circuits into 1, 4 circuits into 1 or 20 circuits into 1. I'm thinking there might be an easier way. What apparatus would you guys suggest, or do you think I'm already on the right path?

 

[KrisBlueNZ]

I'm not exactly sure what you want to do, but I wouldn't be connecting 30 AWG magnet wire to that type of connector - my gut feeling is that every time anything moves, the wire will bend, close to the solder joint, and eventually it will break.

Personally, I would run the wires from the LEDs to the connection points along common routes, and twist together (not tightly) wires that are going to the same connection point. So as the bundle gets closer to the connection point, it gets thicker and more robust. Then at the connection point, I would feed them through a piece of somewhat rigid insulation or "spaghetti" sleeving, solder them all to the connector pin (whatever connector you decide to use), and slide the sleeving up to the connector so that it reinforces the joint and prevents the wires from bending close to the joint.

Of course this would not be modular. If you needed to replace any wire, you would have to desolder the whole lot, un-twist them, replace the wire, re-twist and re-solder. For this reason I would use the thickest wire I could reasonably get away with. 30 AWG seems very thin to me.

Again, I'm not sure what you're aiming for, so please take my suggestions with a grain of salt.

 

[robertgzzzt]

(whatever connector you decide to use)

That's what I'm asking advice on....what connectors to use to bring several positive and negative 30awg magnet wires into ONE positive and ONE negative 22awg hookup wire.

Personally, I would run the wires from the LEDs to the connection points along common routes, and twist together (not tightly) wires that are going to the same connection point. So as the bundle gets closer to the connection point, it gets thicker and more robust. Then at the connection point, I would feed them through a piece of somewhat rigid insulation or "spaghetti" sleeving, solder them all to the connector

That's exactly what I intend to do. I was just asking for advice on the best type of connectors to use to give me a clean, neat and durable junction.


I'm sorry my post was confusing. I thought I was pretty clear, but apparently not. Did you click on the links?

 

[robertgzzzt]

Oh and just so you know....when I solder the magnet wire to the LED, I melt off about an inch of the insulation with my iron, then I wrap that naked wire around the leg of the LED (or resistor) about 10 times, then solder it, then after I've soldered all the ones I need for that circuit, I mix up some 5 minute epoxy and coat the entire leg of the led and 1/4" onto the wire with that epoxy, then after the epoxy sets up, I cover the whole thing, including about an inch of wire with tiny 1/16" shrink tubing and shrink it down with a heat gun. In addition to that, I use that very same epoxy to glue all of my wires down to the inside of the model, about every two inches, so that it won't be flopping around inside there.

I assure you, all my wiring is going to be very secure and will not be breaking on me. Once this model is sealed, there's no going back to "replace a wire", that's why I'm trying to be as diligent as possible to make sure everything is secure.

 

[KrisBlueNZ]

Yes, I clicked the links and read your post. My feeling is that that type of connector is not suitable for connection to very thin individual wires; they could break while you are mating and unmating the connectors. If you want to use that type of connector, I would use a 2-pin connector and common up the wires inside the model. This restricts your future options for controlling LEDs individually though.

What you're doing with the LED leads sounds good, but you don't really have the option of doing that with those connectors. My suggestion of bundling the wires together is simply for rigidity; the wires would provide mutual strain relief. After that, it doesn't matter what kind of connector you use, although I would go for one that (a) has longer terminations to attach the wire to, (b) has a shorter travel distance for connecting and disconnecting, so that wire movement is minimised, (c) has some kind of locating system so it's impossible to mate the plug and socket the wrong way round or offset, and (d) has a higher density, if you want separate connections to all the LEDs.

For an example, go to digikey.com, go to Product Index > Connectors, Interconnects > Rectangular - Board to Board Connectors - Headers, Receptacles, Female Sockets, and in the "Series" box, choose "CLP", then click Apply Filters. Have a look at those options.

I suppose that pin strip approach might work well if you can attach the pin strip physically to part of the model, and use the socket strip, with heavier wires attached, for the connection to the drive circuitry. If that was what you meant, then I didn't get that impression from your post; that's why I said I wasn't sure what you wanted to do.

If you use multiple pins, you could remove some pins and block up some holes to protect against offset or reversed connection if you think that's necessary.

 

[robertgzzzt]

they could break while you are mating and unmating the connectors If you want to use that type of connector, I would use a 2-pin connector and common up the wires inside the model

The magnet wire isn't as fragile as you think, especially coated in epoxy and wrapped in shrink tubing, but anyway, I don't know what I was thinking. I won't have any need for "plugging and unplugging" inside the model, once the model is sealed shut, there's no going back in without destroying it. I just need to junction many wires into one single set of positive and negative wires. That junction will be permanent. Even though the connector will be hidden inside the model, I still want to do it in a professional manner. I could just twist all the wires together and solder them to the hookup wire, but that would be shade-treeism, if that's a word.

This restricts your future options for controlling LEDs individually though.

I won't be needing to control LEDs individually.

The model will be mounted on a 6 inch piece of 3/8" aluminum tubing, which fits into a 7" x 10" styrene plastic display base that came with the model. I'm going to mount this base on a board about the same length and width and my circuit boards will be mounted on this board underneath the model display base . One of them is the blinker board with the Mosfet that you helped me with. It'll be controlling 10 LEDs inside the model, but I don't want to bring 20 wires out of model, when I can create a junction inside the model, turning those 20 magnet wires into 2 (one positive and one negative) 22awg hookup wires coming down the tube and hooking to the circuit board.


There's another circuit board, very similar to the blinker, it controls 4 strobing LEDs. I'm going to junction those 8 wires into 2 (one positive and one negative) 22awg hookup wires inside the model, then bring those two hookup wires down the tube to the circuit board.

There's two more small boards, but I won't go into detail, you get the idea. There's also a bunch of static LEDs, they don't blink or strobe or anything. They are just on all the time when switched on.

I just don't want a rat's nest of wires coming out of the model. I was only asking for advice on connectors. As always, I really appreciate your help