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Need a circuit board and casing **help**
by tokyo » Wed Dec 01, 2010 10:44 pm
- tokyo
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Ok, I am working on a prototype. I have everything I need, except the circuitboard that will control the order of the functions and the plastic casing that will house it.
Is there a place I can buy something like this?
It is very simple. I need it to have a default circuit that remains on until a button is pressed. At which time the main circuit is switched off and a secondary circuit is turned on. The secondary circuit remains on until an external switch turns it off, at which time the main circuit is turned back on and remains on until the button is pressed again.
Am I going to be able to find this somewhere? Or even just the plastic casing which I can insert the circuit board into?
Is there a place I can buy something like this?
It is very simple. I need it to have a default circuit that remains on until a button is pressed. At which time the main circuit is switched off and a secondary circuit is turned on. The secondary circuit remains on until an external switch turns it off, at which time the main circuit is turned back on and remains on until the button is pressed again.
Am I going to be able to find this somewhere? Or even just the plastic casing which I can insert the circuit board into?
Re: Need a circuit board and casing **help**
by JoeWaisman » Thu Dec 02, 2010 12:19 am
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JoeWaisman - Green Belt
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Tokyo, there is an extremely common chip that EXACTLY what you're looking for. The chip is an "S-R Latch" and the most common is a 74 279 chip. *
The output unfortunately will only be 5 volts (max), so you'd need to amplify the output or use it to power a relay.
Many first year computer science and electrical engineering students will have taken a "digital logic" class that explains exactly how to do this. Finding cheap, local help shouldn't be difficult.
Breadboards are usually better for individual prototypes. I've purchased these at Radio Shack and Fry's Electronics.
*There will be a bunch of letters in front of, between and after the numbers they aren't usually important. They specify the manufacturer, model revision, and technology used to create the specific chip.
The output unfortunately will only be 5 volts (max), so you'd need to amplify the output or use it to power a relay.
Many first year computer science and electrical engineering students will have taken a "digital logic" class that explains exactly how to do this. Finding cheap, local help shouldn't be difficult.
Breadboards are usually better for individual prototypes. I've purchased these at Radio Shack and Fry's Electronics.
*There will be a bunch of letters in front of, between and after the numbers they aren't usually important. They specify the manufacturer, model revision, and technology used to create the specific chip.
___________________________________________
"The horse is here to stay but the automobile is only a novelty, a fad."
Fun links:
*http://www.scribd.com/doc/441708/Bad-Predictions-About-Great-Inventions
"The horse is here to stay but the automobile is only a novelty, a fad."
Fun links:
*http://www.scribd.com/doc/441708/Bad-Predictions-About-Great-Inventions
Re: Need a circuit board and casing **help**
by tokyo » Thu Dec 02, 2010 3:02 am
- tokyo
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Great, thanks for the help.
I found several sources for S-R Latch chips. Here is a link to one of them:
http://uk.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=0640147&cm_sp=PP-_-PPLL-_-0640147
How would I use this chip to achieve what I want? Would I insert it into a breadboard and attach the wires connecting each circuit through the breadboard? Is there a source that explains this so I can apply it to my prototype?
I found several sources for S-R Latch chips. Here is a link to one of them:
http://uk.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=0640147&cm_sp=PP-_-PPLL-_-0640147
How would I use this chip to achieve what I want? Would I insert it into a breadboard and attach the wires connecting each circuit through the breadboard? Is there a source that explains this so I can apply it to my prototype?
Re: Need a circuit board and casing **help**
by JoeWaisman » Thu Dec 02, 2010 11:31 am
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JoeWaisman - Green Belt
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- Joined: Tue Dec 29, 2009 4:10 pm
Quick notes: Where possible you should use TTL chips. They're less sensitive to static, but require a 5v power supply.
When using a bread board, make sure you use SOLID wire.
For a full circuit you would need:
1) 2 Push Buttons (2 terminal)
2) A 7805 chip (5 volt DC voltage regulator) http://www.electrokits.com/downloads/pd ... rchild.pdf
3) A 7404 chip (hex inverter) http://en.wikipedia.org/wiki/Inverter_(logic_gate)
4) A 74270 chip (SR Latch) http://docs-europe.electrocomponents.co ... 0a3a93.pdf
5) 2 resistors in the 1k ohm to 10k ohm range.
To assemble the circuit you would:
1) Connect the battery output to the 7805 - 5 volt regulator. Connect positive battery output to the 7805 "input", and battery ground to the 7805 ground.
2) Connect ground from the battery or 7805 to ground on the circuit board, and "output" from the 7805 to power on the circuit board. Most circuit boards have a red "power" column and a black "ground column." You now have 5v available on the breadboard.
3) Connect the power column to VCC on both your 7404 inverter and 74279 SR latch chips. Connect ground from the breadboard to "ground" or "vss" on the 7404 and 74279.
4) Connect power to one of the terminals for each push button.
5) Connect ground to the free terminal for each push button, but put the resistor in line with each.
6) Connect the push buttons to the 74279 chip: One grounded (via resistor) terminal of each push button terminal connects to 2R the other to 2S. This circuits a bit weird if you haven't done this before...I'll explain in a bit.*
7) Connect the output 2Q from the 74279 chip to A1 on the 7404 hex inverter.
Connect your outputs 2Q (74279) and Q1 (7404) to relays that will drive your 2 circuits....you're done.
*This circuits works because the logic chips require a "low" or "high" signal. High comes from the positive terminal, low from ground. When the button is pushed and power goes "high" a very small amount of voltage also drains to ground (due to the resistor), but the vast majority is available as an input to the chip. When the button is not pressed the "ground" passes the "low" signal.
When using a bread board, make sure you use SOLID wire.
tokyo wrote:How would I use this chip to achieve what I want? Would I insert it into a breadboard and attach the wires connecting each circuit through the breadboard? Is there a source that explains this so I can apply it to my prototype?
For a full circuit you would need:
1) 2 Push Buttons (2 terminal)
2) A 7805 chip (5 volt DC voltage regulator) http://www.electrokits.com/downloads/pd ... rchild.pdf
3) A 7404 chip (hex inverter) http://en.wikipedia.org/wiki/Inverter_(logic_gate)
4) A 74270 chip (SR Latch) http://docs-europe.electrocomponents.co ... 0a3a93.pdf
5) 2 resistors in the 1k ohm to 10k ohm range.
To assemble the circuit you would:
1) Connect the battery output to the 7805 - 5 volt regulator. Connect positive battery output to the 7805 "input", and battery ground to the 7805 ground.
2) Connect ground from the battery or 7805 to ground on the circuit board, and "output" from the 7805 to power on the circuit board. Most circuit boards have a red "power" column and a black "ground column." You now have 5v available on the breadboard.
3) Connect the power column to VCC on both your 7404 inverter and 74279 SR latch chips. Connect ground from the breadboard to "ground" or "vss" on the 7404 and 74279.
4) Connect power to one of the terminals for each push button.
5) Connect ground to the free terminal for each push button, but put the resistor in line with each.
6) Connect the push buttons to the 74279 chip: One grounded (via resistor) terminal of each push button terminal connects to 2R the other to 2S. This circuits a bit weird if you haven't done this before...I'll explain in a bit.*
7) Connect the output 2Q from the 74279 chip to A1 on the 7404 hex inverter.
Connect your outputs 2Q (74279) and Q1 (7404) to relays that will drive your 2 circuits....you're done.*This circuits works because the logic chips require a "low" or "high" signal. High comes from the positive terminal, low from ground. When the button is pushed and power goes "high" a very small amount of voltage also drains to ground (due to the resistor), but the vast majority is available as an input to the chip. When the button is not pressed the "ground" passes the "low" signal.
___________________________________________
"The horse is here to stay but the automobile is only a novelty, a fad."
Fun links:
*http://www.scribd.com/doc/441708/Bad-Predictions-About-Great-Inventions
"The horse is here to stay but the automobile is only a novelty, a fad."
Fun links:
*http://www.scribd.com/doc/441708/Bad-Predictions-About-Great-Inventions
Re: Need a circuit board and casing **help**
by JoeWaisman » Thu Dec 02, 2010 11:42 am
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JoeWaisman - Green Belt
- Posts: 234
- Joined: Tue Dec 29, 2009 4:10 pm
Here's a decent video that shows an extremely similar circuit: http://www.youtube.com/watch?v=mo4Lq0DvJ68
They're using a single chip of NOR gates...which is better for using a single chip. It is however worse if you haven't worked with digital logic before because explaining how things work or figuring out how to fix something gone wrong is more complex. I also suspect that the 74279 chip is debounced, while the circuit in the youtube video probably isn't.
They're using a single chip of NOR gates...which is better for using a single chip. It is however worse if you haven't worked with digital logic before because explaining how things work or figuring out how to fix something gone wrong is more complex. I also suspect that the 74279 chip is debounced, while the circuit in the youtube video probably isn't.
___________________________________________
"The horse is here to stay but the automobile is only a novelty, a fad."
Fun links:
*http://www.scribd.com/doc/441708/Bad-Predictions-About-Great-Inventions
"The horse is here to stay but the automobile is only a novelty, a fad."
Fun links:
*http://www.scribd.com/doc/441708/Bad-Predictions-About-Great-Inventions
Re: Need a circuit board and casing **help**
by tokyo » Sat Dec 04, 2010 3:30 am
- tokyo
- White Belt
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- Joined: Sat Nov 20, 2010 3:54 pm
Thanks for the help.
I am a little confused though. What is the second button for?
There should only be one button. After that button is pressed everything else is automated. I'm sorry if this is a silly question. I have almost no experience with this.
Just to make sure there is no confusion, here is a better description of how that unit should run.
There are two circuits, each controls a seperate task. Circuit 1 is the default circuit that remains on at all times except when Circuit 2 is on. When the button is pressed Circuit 1 shuts off and Circuit 2 turns on. When the task controlled by Circuit 2 is complete it will be automatically turned off by an external float switch. When the float switch turns off, power needs to be removed from Circuit 2 and Circuit 1 needs to be turned on. This would complete the process and it should not start over until the button is pressed again.
I am a little confused though. What is the second button for?
There should only be one button. After that button is pressed everything else is automated. I'm sorry if this is a silly question. I have almost no experience with this.
Just to make sure there is no confusion, here is a better description of how that unit should run.
There are two circuits, each controls a seperate task. Circuit 1 is the default circuit that remains on at all times except when Circuit 2 is on. When the button is pressed Circuit 1 shuts off and Circuit 2 turns on. When the task controlled by Circuit 2 is complete it will be automatically turned off by an external float switch. When the float switch turns off, power needs to be removed from Circuit 2 and Circuit 1 needs to be turned on. This would complete the process and it should not start over until the button is pressed again.
Re: Need a circuit board and casing **help**
by JoeWaisman » Sun Dec 05, 2010 1:40 am
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JoeWaisman - Green Belt
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- Joined: Tue Dec 29, 2009 4:10 pm
First, you are very welcome 
.
It seems my initial understanding of your circuit needs was off. As you said the 2nd button would not be necessary.
You would actually do everything the same, except you would use the output of the float switch as the input of "2R" on the 74279 chip (see step 6 above). The inputs of the 74279 need to be within a certain voltage range...this varies with each specific model of the 74279 chip. Bottom line is you might have to amplify or decrease the voltage output of the float switch. You might also have to convert the float switch output from AC to DC.
.It seems my initial understanding of your circuit needs was off. As you said the 2nd button would not be necessary.
You would actually do everything the same, except you would use the output of the float switch as the input of "2R" on the 74279 chip (see step 6 above). The inputs of the 74279 need to be within a certain voltage range...this varies with each specific model of the 74279 chip. Bottom line is you might have to amplify or decrease the voltage output of the float switch. You might also have to convert the float switch output from AC to DC.
___________________________________________
"The horse is here to stay but the automobile is only a novelty, a fad."
Fun links:
*http://www.scribd.com/doc/441708/Bad-Predictions-About-Great-Inventions
"The horse is here to stay but the automobile is only a novelty, a fad."
Fun links:
*http://www.scribd.com/doc/441708/Bad-Predictions-About-Great-Inventions
Re: Need a circuit board and casing **help**
by Scrupulous » Tue Dec 14, 2010 11:20 am
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Scrupulous - Black Belt
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- Joined: Sun Jan 21, 2007 7:32 pm
- Location: United States
Joe, I had no idea you were quite the electronics guru...
________________
I'm Ken Campbell, a registered US patent practitioner at the Affordable Patent Service™.
As a forum moderator, though, any input I provide should be considered general information, and not legal advice. The ideas I express are not necessarily the opinions of InventorSpot.com or its affiliates. In general, any action taken as a result of information, analysis, or advice from any forum members on this site is ultimately the user's responsibility.
I'm Ken Campbell, a registered US patent practitioner at the Affordable Patent Service™.
As a forum moderator, though, any input I provide should be considered general information, and not legal advice. The ideas I express are not necessarily the opinions of InventorSpot.com or its affiliates. In general, any action taken as a result of information, analysis, or advice from any forum members on this site is ultimately the user's responsibility.
Re: Need a circuit board and casing **help**
by JoeWaisman » Wed Dec 15, 2010 5:05 pm
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JoeWaisman - Green Belt
- Posts: 234
- Joined: Tue Dec 29, 2009 4:10 pm
Thanks, I'm working on becoming an electronics guru...you wouldn't know that though because I never bothered to fill out my profile completely. I love working with analog/digital logic (the topic above), and am learning other elements of electrical engineering. If you need a device that does x,y, and z, I can often build it via digital logic, or a programmed embedded chip...though I'm still building experience with the latter of the two.
I have worked in product support, project management and SQA roles for Symantec (1998-2003). I wasn't much of a people person though, which is bad when you're in a management position. Toward the end the dot com's went bust, the market tanked, and I realized I was making more $ than many who had been doing the same job for years...about 6 months after that revelation I was let go. I left having worked with the best marketing, project and development managers in the company (just to name a few). Since then I've spent 6 years as a waiter, and bartender and am much more comfortable interacting with others. I'm presently a junior, working towards my electrical engineering degree.
There! Now if you don't know something about me, it's not because I held anything back.
I have worked in product support, project management and SQA roles for Symantec (1998-2003). I wasn't much of a people person though, which is bad when you're in a management position. Toward the end the dot com's went bust, the market tanked, and I realized I was making more $ than many who had been doing the same job for years...about 6 months after that revelation I was let go. I left having worked with the best marketing, project and development managers in the company (just to name a few). Since then I've spent 6 years as a waiter, and bartender and am much more comfortable interacting with others. I'm presently a junior, working towards my electrical engineering degree.
There! Now if you don't know something about me, it's not because I held anything back.
___________________________________________
"The horse is here to stay but the automobile is only a novelty, a fad."
Fun links:
*http://www.scribd.com/doc/441708/Bad-Predictions-About-Great-Inventions
"The horse is here to stay but the automobile is only a novelty, a fad."
Fun links:
*http://www.scribd.com/doc/441708/Bad-Predictions-About-Great-Inventions
Re: Need a circuit board and casing **help**
by Scrupulous » Sat Dec 18, 2010 3:46 pm
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Scrupulous - Black Belt
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- Joined: Sun Jan 21, 2007 7:32 pm
- Location: United States
Good stuff, Joe...
________________
I'm Ken Campbell, a registered US patent practitioner at the Affordable Patent Service™.
As a forum moderator, though, any input I provide should be considered general information, and not legal advice. The ideas I express are not necessarily the opinions of InventorSpot.com or its affiliates. In general, any action taken as a result of information, analysis, or advice from any forum members on this site is ultimately the user's responsibility.
I'm Ken Campbell, a registered US patent practitioner at the Affordable Patent Service™.
As a forum moderator, though, any input I provide should be considered general information, and not legal advice. The ideas I express are not necessarily the opinions of InventorSpot.com or its affiliates. In general, any action taken as a result of information, analysis, or advice from any forum members on this site is ultimately the user's responsibility.
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