Adafruit Push-button Power Switch Breakout - ID: 1400
See attached schematic
I am using your power switch to enable/ disable a load in my Laser Vehicle Guidance Parking system project.
At point A (series current / ampmeter) I measure 6.5 ma. with the Adafruit power switch ON (no load connected ) <--- correction
At point A (series current / ampmeter) I measure 33 ma. with the Adafruit power switch ON (load with Teensy 3,accel only).
At point L (series current / ampmeter) I measure 13 ma. load current with Teensy 3,accel only without the connected laser and darlington.
The Adafruit power switch seems to be consuming/wasting 20 ma. of current which I need for my laser module.
Is the current consumption or draw on the power switch normal ?
If so, how would I reduce this current draw?
Adafruit Push-button Power Switch Breakout - ID: 1400
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Adafruit Push-button Power Switch Breakout - ID: 1400
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Last edited by adafruitandy on Sat Aug 17, 2013 1:51 pm, edited 1 time in total.
- adafruit_support_rick
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Re: Adafruit Push-button Power Switch Breakout - ID: 1400
That would be the red LED drawing the current.adafruitandy wrote:The Adafruit power switch seems to be consuming/wasting 20 ma. of current which I need for my laser module.
Is the current consumption or draw on the power switch normal ?
You could try removing the LED.adafruitandy wrote:If so, how would I reduce this current draw?
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Re: Adafruit Push-button Power Switch Breakout - ID: 1400
That would be the red LED drawing the current.
I think you mean the red LED on adafruits power switch? (my other red LED only draws 1.5 ma)
if so, looking at your schematic of the adafruit power switch you have a 1k resistor in series with the LED.
No knowing the FV of your red LED and using 5V / 1K = 5 ma. <--- this value would be "lower" if the FV is computed properly.
Why do you think it is the LED ?
Is your schematic drawn right ?
Last edited by adafruitandy on Sat Aug 17, 2013 1:40 pm, edited 1 time in total.
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Re: Adafruit Push-button Power Switch Breakout - ID: 1400
I completely fazed on the fact that we even had a schematic posted. I admit, I was assuming the LED was doing that (and we all know what happens when you assume), because well, what else could it be?
I still don't know what else it could be. I'll ping the product engineers...
I still don't know what else it could be. I'll ping the product engineers...
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Re: Adafruit Push-button Power Switch Breakout - ID: 1400
Rick - recheck my initial post for a minor correction
BTW ... I might add that you really need to add a pulldown to ground before the 1K 2N2222 kill input to make sure the proper low level is in the off state.
pFetbecause well, what else could it be
BTW ... I might add that you really need to add a pulldown to ground before the 1K 2N2222 kill input to make sure the proper low level is in the off state.
- adafruit_support_rick
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Re: Adafruit Push-button Power Switch Breakout - ID: 1400
Hey - I'm only a software guy. You're making my head hurt.
I've referred this problem up to the smart people.
I've referred this problem up to the smart people.
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Re: Adafruit Push-button Power Switch Breakout - ID: 1400
The current consumption at point A, before the boost converter, gives excessive readings.
The current consumption should be done after the boost converter. CASE CLOSE
BTW ... You still need to add a pulldown to ground before the 1K 2N2222 kill input to make sure the proper low level is in the off state.
The current consumption should be done after the boost converter. CASE CLOSE
BTW ... You still need to add a pulldown to ground before the 1K 2N2222 kill input to make sure the proper low level is in the off state.
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Re: Adafruit Push-button Power Switch Breakout - ID: 1400
Why I stick to software problems.adafruitandy wrote:The current consumption at point A, before the boost converter, gives excessive readings.
The current consumption should be done after the boost converter. CASE CLOSE
I passed that along to the product engineers.adafruitandy wrote:BTW ... You still need to add a pulldown to ground before the 1K 2N2222 kill input to make sure the proper low level is in the off state.
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Re: Adafruit Push-button Power Switch Breakout - ID: 1400
And the product engineers respond:adafruit_support_rick wrote:adafruitandy wrote:
BTW ... You still need to add a pulldown to ground before the 1K 2N2222 kill input to make sure the proper low level is in the off state.
I passed that along to the product engineers.
BJT transistors don't need pulldowns, they are current-mode devices.
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Re: Adafruit Push-button Power Switch Breakout - ID: 1400
Hi,
is there a way to modify the circuit so to switch on or off someone would need to hold the button pushed for 2-3 seconds? I would like to prevent some "accidentially" switching of my circuit. I want the user to hold the button for a specific time to perform a switchover ...
Any ideas?
is there a way to modify the circuit so to switch on or off someone would need to hold the button pushed for 2-3 seconds? I would like to prevent some "accidentially" switching of my circuit. I want the user to hold the button for a specific time to perform a switchover ...
Any ideas?
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Re: Adafruit Push-button Power Switch Breakout - ID: 1400
I don't think so.
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Re: Adafruit Push-button Power Switch Breakout - ID: 1400
It's possible to build a circuit that requires a long contact period before triggering an event, but the parts you'd have to add would be more complicated than the existing switch.
- konfu
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Re: Adafruit Push-button Power Switch Breakout - ID: 1400
Any circuits diagrams or hints to this other circuit? My workbench is well equipped with all kind of parts but my circuit collection isn't in this case :-)
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Re: Adafruit Push-button Power Switch Breakout - ID: 1400
You'd need something like this:
In the timing section, the transistor is normally turned on, shorting the top of the 4.7uF capacitor to GND. Pressing the button shuts off the transistor, allowing the 1M resistor to start charging the cap. Releasing the button lets the transistor turn on again, and will drain any charge in the cap in a few microseconds. If you release the switch at any time before the trigger trips, you have to start over again from zero.
For the trigger, I drew an LM339 comparator since those are common. The LM339 has open-collector output, so it needs a pull-up resistor in order to work. You can replace the LM339 with a 555 chip, connecting the output of the timing section to the THRESHOLD pin and the 10k resistor to the DISCHARGE pin. The trigger's output is normally HIGH, but will go LOW when the capacitor voltage rises above Vref.
You'd connect points A and B of the analog switch section to opposite sides of the Pushbutton Power Switch's tact switch. The orientation doesn't matter, and that's kind of the problem: A and B will alternate being HIGH and LOW, meeting at VCC/2 when the switch is closed. That alternation is critical to making the PBS work, and it takes more than one transistor to handle current that can flow both ways. You could do the same thing with an analog switch chip like the 74*4066 or a reed relay.
In the timing section, the transistor is normally turned on, shorting the top of the 4.7uF capacitor to GND. Pressing the button shuts off the transistor, allowing the 1M resistor to start charging the cap. Releasing the button lets the transistor turn on again, and will drain any charge in the cap in a few microseconds. If you release the switch at any time before the trigger trips, you have to start over again from zero.
For the trigger, I drew an LM339 comparator since those are common. The LM339 has open-collector output, so it needs a pull-up resistor in order to work. You can replace the LM339 with a 555 chip, connecting the output of the timing section to the THRESHOLD pin and the 10k resistor to the DISCHARGE pin. The trigger's output is normally HIGH, but will go LOW when the capacitor voltage rises above Vref.
You'd connect points A and B of the analog switch section to opposite sides of the Pushbutton Power Switch's tact switch. The orientation doesn't matter, and that's kind of the problem: A and B will alternate being HIGH and LOW, meeting at VCC/2 when the switch is closed. That alternation is critical to making the PBS work, and it takes more than one transistor to handle current that can flow both ways. You could do the same thing with an analog switch chip like the 74*4066 or a reed relay.
Please be positive and constructive with your questions and comments.