Is this schematic ok to do a short power on delay for a small MCU

[audioelectrics]

Hi Guys and Gals,

I am just trying to create a bit of a power on delay for a small processor and wonder if this design is ok, I am a total nerd with this analog stuff and need like 2-5 seconds delay.

 

[srizbf]

the circuit will have delay of more than 10-12 seconds .
If that delay is tolerable then it is ok.
The current requirement of your controller is dependent on bc857.
Did you simulate your delay circuit ?

what is the voltage at pin 8(Vs+) after the delay ?

 

[audioelectrics]

the circuit will have delay of more than 10-12 seconds .
If that delay is tolerable then it is ok.
The current requirement of your controller is dependent on bc857.
Did you simulate your delay circuit ?

what is the voltage at pin 8(Vs+) after the delay ?

Thank you srizbf for looking,

10-12 seconds is fine, and I could always adjust the 33uf and 660K to adjust it.
I have no idea how to simulate it or even know what the final voltage output would be, i was thinking a few mV less than the supply,

Wanted to run it past some more knowledgeable eyes before I bother to try and make a little PCB, I am using very old software to draw schematics and do the PCB..and of course a bit of a noob with analog.

I could always change the BC857 for something a bit more beefy too.

Can you recommend some application to simulate such circuits.

Many Thanks

 

[srizbf]

Leave the simulation part now.( it will consume more time to learn and debug if you are new to it.)

If at all , if you want to make it , first make breadboard version and test it before making a pcb.
This will save you lot of time and money.

No problem with old schematic or pcb software as long as it meets your needs.

one more , do you want to apply the supply voltage to the microcontroller delayed , or will it be good to apply the RESET signal delayed ?

Based on your final application you can select.

 

[audioelectrics]

Leave the simulation part now.( it will consume more time to learn and debug if you are new to it.)

If at all , if you want to make it , first make breadboard version and test it before making a pcb.
This will save you lot of time and money.

No problem with old schematic or pcb software as long as it meets your needs.

one more , do you want to apply the supply voltage to the microcontroller delayed , or will it be good to apply the RESET signal delayed ?

Based on your final application you can select.

Hi Srizbf, thank you for your guidance,

Yes a breadboard is a great idea, especially for working on the delay period. Still does it exist simulation software which could work on small schematics like this one?

I must apply the power to the MCU with a delay, nothing else will exist to toggle a reset pin.

The system will be 5V powered & the MCU will be on a very small board containing 3.3V regulation. I actually eventual plan is to place the power on delay also on the same MCU board so that a hardware delay exists.

 

[BradtheRad]

Still does it exist simulation software which could work on small schematics like this one?

Falstad's animated interactive simulator is easy to work with. Before long you'll be able to draw a circuit, create scope traces, change values. It supports the components in your schematic, and a few generic IC's.

Free to download and use at:

www.falstad.com/circuit

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Also consider LTSpice (Spice variant by Linear Technology, free to download and use). It frequently gets favorable mention at this forum. It supports sophisticated IC's. Scope traces are easy to examine.