Hi Luka

Linear for sure has a more retro feel to it and will still be going in 25 
years, but if you are already down the switching path then I think this one 
deals with the most immediate issues. It has a nice heatsinkable MOSFET in 
it, and the active pull down and the current sense resistors.

If I am not wrong, the original designer might be in this group, and I 
believe offers that design on Ebay. Not trying to hard sell you, just 
saying... You could save yourself an evening or two, and give him a nod of 
thanks as well.

I'm working on a switching design based around an ATTiny at the moment, but 
this is just because of my perverse nature...


On Wednesday, 23 September 2015 22:06:21 UTC+2, Luka C wrote:
>
>
> <https://lh3.googleusercontent.com/-v0bjuN0XQWg/VgMGNJhH7bI/AAAAAAAAAF0/vLSC_u2tz3M/s1600/mc34063_mk15cm1.gif>
>
>
> The picture seems to be moved, so this is the PS I'm planning to implement 
> into my design. Do you think this one is fine for 4x IN-14 and 4x INS-1?
> Thanks.
>
> Dana srijeda, 23. rujna 2015. u 20:39:23 UTC+2, korisnik Luka C napisao je:
>>
>>
>> Okay, so I read all the advices and thank you all for explaining the 
>> problems with this power supply. Since the board is extremely small and I 
>> will be installing it in a very thin housing, I don't really have much 
>> space to do modifications on it. So, I'll implement PS in my PCB design and 
>> solder its components on it.
>> I'd like to know if you could check this PS and see if it should be ok 
>> for my clock (4x IN-14 and 4x INS-1 tubes)?
>>
>> Thanks a lot in advance.
>>
>>
>> <https://lh3.googleusercontent.com/-b9BU5T8kpY4/VgLxiEHdmZI/AAAAAAAAAFk/x7hJ0aVd_dA/s1600/mc34063_mk15cm1.gif>
>>
>> Dana utorak, 22. rujna 2015. u 21:23:39 UTC+2, korisnik gregebert napisao 
>> je:
>>>
>>> Why not just use a totem-pole pre-driver for the MOSFET ?
>>>
>>> BTW, this touches on a challenge when designing HV drivers, whether they 
>>> are for DC-DC converters or driving cathodes. Most high-voltage NMOS 
>>> devices (~400V)  need 5-6 volts for solid gate turn-on, yet logic-levels on 
>>> most micro-controllers and FPGAs are only 1.2 to 3.3volts.  That leaves a 
>>> few options:
>>>
>>> 1. Use high-voltage logic, such as 4000-series CMOS, to drive HV NMOS. 
>>> My first nixie clock does this.
>>>
>>> 2. Use NPN drivers; you can easily design constant-current drivers 
>>> running from 3.3V. I've used surface-mount devices with 2 NPNs inside, and 
>>> they are rated at 250V.
>>>
>>> 3. Use a level-shifter between your logic and the driver. I'm doing this 
>>> on my current design with a HV5530.
>>>
>>> 4. Find a device with a low-voltage gate. Good luck on this; most 
>>> logic-levels NMOS devices only handle 60V or less. If you also want low Rds 
>>> (necessary for DC-DC converters), you have even fewer options.
>>>
>>> 5. Pull-up resistor. Ugghhh... It will work, but you will burn more 
>>> power. Could be dangerous for a DC-DC converter if the logic/software 
>>> turning off the gate goes haywire, which would lead to large 
>>> current/burnout.
>>>
>>>
>>> I advise against relying upon the voltage-drop of the nixie tube to 
>>> protect the driver, though this is commonly done with designs using the 
>>> 74141. I always select my driver to handle the maximum-possible anode 
>>> supply, and add margin above that. I've never had a fried driver, ghosting, 
>>> etc. Parasitic capacitance and leakage can stress drivers above their 
>>> maximum ratings, which will lead to premature failure.
>>>
>>

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