Hello,
I built PSU for my chip amp using torodial transformer that has 160VA rating, primary winding - 230V and 2x secondary winding 40V-2A. But i do not know how to select right fuse (F1). Thanks.
I built PSU for my chip amp using torodial transformer that has 160VA rating, primary winding - 230V and 2x secondary winding 40V-2A. But i do not know how to select right fuse (F1). Thanks.
The fuse must allow the maximum steady loading (160W) plus some transformer losses. 1A (slow) should do. The problem is if the start-up surge (from the 2x10000uF) may blow the fuse? Honestly, I have always carried out this experiment and normally the fuse works.
There may be people having a more scientific approach.
There may be people having a more scientific approach.
Simulate the circuit in PSUD and check the current graph. Look for any spikes and pick the biggest spike as the rating for your fuse. Add a bit and try that first. If it blows at switch on try the next up until you found a rating that works. Mark that rating on the power supply. If the fuses don't stop blowing no matter how many steps you go up check your build...
Its a balancing act, not so high a current as to cause a fire should a fault occur and not so low you get nuisance blowing of the fuse.
Once you get above about 15,000uf per rail you are getting into soft start circuit territory.
Once you get above about 15,000uf per rail you are getting into soft start circuit territory.
Cycan, the link below has a process that uses PSUD2 to determine capacitor inrush current and transfer that to the primary side, and then estimate transformer inrush current, and to use that along with standard fuse curves.
Like all electronic design, you can of course just try a few fuse values until one doesn't blow, but if you have the time and incentive then it is a good learning curve to appreciate how fuse selection can be done in more detail.
https://www.dalmura.com.au/static/Valve%20amp%20fusing.pdf
Like all electronic design, you can of course just try a few fuse values until one doesn't blow, but if you have the time and incentive then it is a good learning curve to appreciate how fuse selection can be done in more detail.
https://www.dalmura.com.au/static/Valve%20amp%20fusing.pdf
160VA/230V is 0.7 Amps. You want to be over that.
At the other extreme, you MUST protect your lamp-cord. This is typically 10+ Amps max safe.
More than 0.7A but way under 10A leads to about 1 Amp, maybe 1.5 or 2A if the turn-on surge is very big.
At the other extreme, you MUST protect your lamp-cord. This is typically 10+ Amps max safe.
More than 0.7A but way under 10A leads to about 1 Amp, maybe 1.5 or 2A if the turn-on surge is very big.
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