I really like the included 555 circuit. It produces a nice 15-25 second switch off timer.

I live in the USA, any thoughts on where I can get one of those pretty printed circuit boards designed to let you solder the specific components instead of just a basic board where you have to think? Every time I solder on a basic breadboard it fails. I don't need 100's, just like 1 - 5 depending on cost, just to play with.

To the question -
You'll notice this circuit calls for two LED's, which made me wonder, can't I use two transistors instead in some way to let me power one device when the 555 timer is high, and then another device when it's low? I'd use a transistor so it could handle more power.

I can't find a schematic that does that, but it seems like something every engineer would need at some point, so I'm not sure why I don't see that circuit everywhere. The problem using it as is, is your load has to be low power or you'll hurt the 555 timer I think.

I tried making my own circuit to do this with one NPN and one PNP transistor in place of the LED's but found out they got super hot Apparently, that just keeps power continually running through the transistors haha.

Thanks!

 

Can you design a PCB layout for this circuit? There are many resources that will make PCB boards for any design you supply.

ExpressPCB. SEEED. OshPark.

Then there’s the issue of how you’re going to design the PCB board. ExpressPCB has a free download of their design software. The others require you to design in a third-party piece of software. I use DipTrace.

Take a look at the above options. And then let us know if they work for you and why. And if you think they won’t, let us know why.

 

I really like the included 555 circuit. It produces a nice 15-25 second switch off timer.

I live in the USA, any thoughts on where I can get one of those pretty printed circuit boards designed to let you solder the specific components instead of just a basic board where you have to think? Every time I solder on a basic breadboard it fails. I don't need 100's, just like 1 - 5 depending on cost, just to play with.

To the question -
You'll notice this circuit calls for two LED's, which made me wonder, can't I use two transistors instead in some way to let me power one device when the 555 timer is high, and then another device when it's low? I'd use a transistor so it could handle more power.

I can't find a schematic that does that, but it seems like something every engineer would need at some point, so I'm not sure why I don't see that circuit everywhere. The problem using it as is, is your load has to be low power or you'll hurt the 555 timer I think.

I tried making my own circuit to do this with one NPN and one PNP transistor in place of the LED's but found out they got super hot Apparently, that just keeps power continually running through the transistors haha.

Thanks!View attachment 175198

So, we can’t tell how you wired the transistors. Post a schematic of how you wired them.

Take a look at optoisolators.

 

can't I use two transistors instead in some way to let me power one device when the 555 timer is high, and then another device when it's low?

Yes. What are the voltage and current requirements of the two devices?

ak

 

I can't find a schematic that does that

A couple of examples.
Component values depend on voltages and currents required.
EDIT: schematic for High and Low inputs.
SG

 

Given the 200 mA output current of a 555, you probably can drop one transistor from each circuit.

ak

 

Maybe this is what you wanted:



The 1N751's are 5.1V Zener diodes. With the resistors shown each transistor will get about 5 ma of base current when on.

 

If the two zeners are 6.2 V each, then there is no time during the 555 output transition when both transistors are on at the same time.

ak

 

So much good information thanks, I'll try to respond to all here:

Can you design a PCB layout for this circuit? There are many resources that will make PCB boards for any design you supply.

ExpressPCB. SEEED. OshPark.

Then there’s the issue of how you’re going to design the PCB board. ExpressPCB has a free download of their design software. The others require you to design in a third-party piece of software. I use DipTrace.

Take a look at the above options. And then let us know if they work for you and why. And if you think they won’t, let us know why.

Great, I'll check it out. I really don't know how to design the circuit so I'll check with the companies and see if they can provide that service for me from the image of my circuit I gave above.

optoisolators - ok I'll have to look into that more, I just read the quick

google description so far and not sure how it applies yet. Apparently, they just separate source power, but I'll need to research it more.

Yes. What are the voltage and current requirements of the two devices?

ak

I don't know yet. I just knew the circuit I supplied only allows for small volt/current so you don't hurt the 555 timers. Let's say I want two devices that will toggle their on/off states based on a 555 output that run at the maximum V and A ratings for a basic NPN / PNP transistor.

A couple of examples.
Component values depend on voltages and currents required.
EDIT: schematic for High and Low inputs.
SG
View attachment 175202

Ok, that's really helpful but each circuit only controls one load. How could I join them so the 555 timer turns the first one on, then switches to the other one? That's the circuitry I'd like, but those examples don't quite get me all the way there.

Maybe this is what you wanted:

View attachment 175212

The 1N751's are 5.1V Zener diodes. With the resistors shown each transistor will get about 5 ma of base current when on.

That looks like a really fun circuit, and yes I think that's what I want. Whats the 190418A DC meaning? Does that suggest up to 8 Amps?

If the two zeners are 6.2 V each, then there is no time during the 555 output transition when both transistors are on at the same time.

ak

What made you think of that? Are you just telling me if I build DickCapples circuit that I need the 5.1v zeners? I thought the zener would just control the direction of the flow of energy.

 

Let's say I want two devices that will toggle their on/off states based on a 555 output that run at the maximum V and A ratings for a basic NPN / PNP transistor.

That is exactly what the two circuits I posted do. They allow for higher Vcc on load then say the 5 volts that controls the 555. Updated schematic shows Load 1 ON when the 555 output is Low. Load 2 is ON when the output is High. Just a couple of examples out of many using NPN and PNP transistors.
SG

 

That is exactly what the two circuits I posted do. They allow for higher Vcc on load then say the 5 volts that controls the 555. Updated schematic shows Load 1 ON when the 555 output is Low. Load 2 is ON when the output is High. Just a couple of examples out of many using NPN and PNP transistor.
SG
View attachment 175237

Ok perfect, I didn't know you can just attach the wire like that to run both circuits - but yet, I think that's EXACTLY what I'm looking for. Did you just make that circuit by drawing it? Because I looked for that and couldn't' find it. At least not in a way I understood it.

 

Did you just make that circuit by drawing it?

Correct.
SG

 

Can you design a PCB layout for this circuit? There are many resources that will make PCB boards for any design you supply.

ExpressPCB. SEEED. OshPark.

Then there’s the issue of how you’re going to design the PCB board. ExpressPCB has a free download of their design software. The others require you to design in a third-party piece of software. I use DipTrace.

Take a look at the above options. And then let us know if they work for you and why. And if you think they won’t, let us know why.

So I looked at them, and ExpressPCB seemed to be the easiest to work with. I downloaded their software and spent some time putting together a board - as seen in the image.

Basically I just made a 555 timer board 99% like a standard breadboard, with the exception that the 555 output gets channeled all the way down the center of the board for less wires needed. That and on the right side I made it so you could put a slider switch to power the board on and off.

I didn't buy it yet, the cost was $150 for 10 boards. Probably a good price, but $15 per board is a little steep for a hobbyist just to tinker with a timer with no real purpose. Maybe next tax refund.

 

They have an option for only 3 boards. It’s something like Mini-Pro...Most of the circuit’s I’ve ordered through them used this option. Should be about $70.

If your circuit is small enough, you might’ve able to fit two boards within the mini size.

You’re picture looks like an experimenters board. Don’t feel constrained. Only include the holes that you need. And lay traces between components so you won’t have to wire them.

Can’t say much now. But ask any questions and I’ll be willing to help.

 

They have an option for only 3 boards. It’s something like Mini-Pro...Most of the circuit’s I’ve ordered through them used this option. Should be about $70.

If your circuit is small enough, you might’ve able to fit two boards within the mini size.

You’re picture looks like an experimenters board. Don’t feel constrained. Only include the holes that you need. And lay traces between components so you won’t have to wire them.

Can’t say much now. But ask any questions and I’ll be willing to help.

Im sure you are right, but that's actually the board I would like because it leaves the field open seeing as I'm not sure exactly where I'm going with this yet. The 150 isn't a bad price if you had a purpose, and I'll probably still pay for it just because I want that project board now. I have some screw down power ties that would fit this correctly, and I can add a switch to the bottom right.

I just have to figure out how you connect the top and bottom copper so that I can run my GND and 555 Output properly without interfering with the other holes. I have it drawn correctly in their software, but I don't want to have to solder components to the top and bottom of the board.

 

Im sure you are right, but that's actually the board I would like because it leaves the field open seeing as I'm not sure exactly where I'm going with this yet. The 150 isn't a bad price if you had a purpose, and I'll probably still pay for it just because I want that project board now. I have some screw down power ties that would fit this correctly, and I can add a switch to the bottom right.

I just have to figure out how you connect the top and bottom copper so that I can run my GND and 555 Output properly without interfering with the other holes. I have it drawn correctly in their software, but I don't want to have to solder components to the top and bottom of the board.

Anytime you have a hole, the top and bottom copper connects. It’s callef a via or through plated hole. When they drill a hole, the inside is plated. If there’s copper on the bottom at that hole, the plating will connect the top and bottom.

 

If you need a general purpose board to try out your circuits, then DO NOT waste your money on a custom board. There are many pre-etched boards that would work for you.

Like:
https://www.amazon.com/Prototype-So...+pcb&qid=1555642319&s=gateway&sr=8-1-fkmrnull

This is bit one example. Search for “PCB Development Board”. At $10-$15 for 50 boards, I’d strongly recommend you investigate this option. Ok, let’s do the math... $12.79 for 50 boards is... umm... is $0.26/board. And you’re willing to pay $15/board! Damn man, you’re paying a 5800% premium. I don’t know about you, but I can’t afford to pay 58 timedbwhat something’s worth

All in jest. Just consider what I’ve presented.

 

I live in the USA, any thoughts on where I can get one of those pretty printed circuit boards designed to let you solder the specific components instead of just a basic board where you have to think? Every time I solder on a basic breadboard it fails. I don't need 100's, just like 1 - 5 depending on cost, just to play with.
View attachment 175198

I got some decent boards from https://jlcpcb.com/ .
As for design Kicad is pretty easy to play around in and its free.

 

Oh ok, so the holes cross over, but the traces are only on the top or bottom.

If you need a general purpose board to try out your circuits, then DO NOT waste your money on a custom board. There are many pre-etched boards that would work for you.

Like:
https://www.amazon.com/Prototype-So...+pcb&qid=1555642319&s=gateway&sr=8-1-fkmrnull

This is bit one example. Search for “PCB Development Board”. At $10-$15 for 50 boards, I’d strongly recommend you investigate this option. Ok, let’s do the math... $12.79 for 50 boards is... umm... is $0.26/board. And you’re willing to pay $15/board! Damn man, you’re paying a 5800% premium. I don’t know about you, but I can’t afford to pay 58 timedbwhat something’s worth

All in jest. Just consider what I’ve presented.

I have a bunch of the Amazon boards, however, if you want to put together something you need to do solder bridges or solder tiny wire jumpers and without all the useful tools it gets hard to do working on tiny things like that.

That dev board I created is set up more like a board where you plug in wires, but I couldn't find any solderable boards like it.

Like this:
https://www.amazon.com/Breadboards-...d&qid=1555686268&s=gateway&sr=8-1-spons&psc=1

 

Hmm, maybe I just found one:
https://www.amazon.com/ProtoSim-400...o&qid=1555686341&s=gateway&sr=8-2-spons&psc=1