[Buck boost converters] Nixie tube clock project

Thread Starter

Diogo Ferreira 2

Joined Mar 16, 2017
20
Hello, I'm trying to make a nixie tube clock project and i am very unsure about the power delivery solutions.

1st problem - Currently in my schematic have a LM7805 ic (with 12v Vin) to power the Ic's, but from my calculations i would be using 236mA from it thus having (12v-5v)*236mA wich results in about 1.65W of dissipation, since i dont want to have a big bulky heat sink im looking for a buck converter that would do the job.

2nd problem - After looking on the internet i found a cool page and schematic of a boost converter (using the IC MC34063A) from 12vdc to 180vdc which is exactly what i needed to power the nixie tubes. the problem is that i dont have enough knowledge to check if that circuit would do what i want.

3rd and final problem - Can someone help me check if the boost circuit works and help me design a buck converter with the same type of ic used in the boost converter?

My project with schematic is the following link:
https://easyeda.com/diogoferreira889/nixie-clock

Thanks you in advance
Diogo Ferreira
 

Thread Starter

Diogo Ferreira 2

Joined Mar 16, 2017
20
Another question this one came from a weird brainstorm while watching some youtube videos
Can i use a voltage divider at the input of the LM7805 to reduce Vin thus reducing the power dissipation?
 

Marley

Joined Apr 4, 2016
279
That boost circuit probably works OK. Though to be honest I don't like the choice of IC used because it doesn't drive the MOSFET properly.
Don't use a voltage divider on the input to the LM7805. For lowest power dissipation replace with a simple buck converter like the attached.
 

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KeithWalker

Joined Jul 10, 2017
413
Hello, I'm trying to make a nixie tube clock project and i am very unsure about the power delivery solutions.

1st problem - Currently in my schematic have a LM7805 ic (with 12v Vin) to power the Ic's, but from my calculations i would be using 236mA from it thus having (12v-5v)*236mA wich results in about 1.65W of dissipation, since i dont want to have a big bulky heat sink im looking for a buck converter that would do the job.

2nd problem - After looking on the internet i found a cool page and schematic of a boost converter (using the IC MC34063A) from 12vdc to 180vdc which is exactly what i needed to power the nixie tubes. the problem is that i dont have enough knowledge to check if that circuit would do what i want.

3rd and final problem - Can someone help me check if the boost circuit works and help me design a buck converter with the same type of ic used in the boost converter?

My project with schematic is the following link:
https://easyeda.com/diogoferreira889/nixie-clock

Thanks you in advance
Diogo Ferreira
Here is a buck circuit. It is for a car USB charger that will do just what you want.
https://dmohankumar.wordpress.com/2016/10/04/car-usb-charger-using-mc-34063-start-up-project-40/
 

mvas

Joined Jun 19, 2017
538
1st problem - Currently in my schematic have a LM7805 ic (with 12v Vin) to power the Ic's, but from my calculations i would be using 236mA from it thus having (12v-5v)*236mA wich results in about 1.65W of dissipation, since i dont want to have a big bulky heat sink im looking for a buck converter that would do the job.
They make a 3-Terminal 5 Volt Switching Regulator that directly replaces the 7805.
 
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