Yes, the 22K will work fine, it will just take longer for the caps to discharge.
Keep that in mind when you are working on your amp. Make sure you wait long enough before touching the PS. Easy enough to throw a LED w/ resistor on board to verify discharge status.
Ron
I figured it out. It was so straightforward that I feel silly even posing the question.
Question on # of Dual Common Cathode diode
Hi,
In Pass F5T paper, power supply shows only 4 (Dual Common Cathode) diodes(MUR3020W).
In the PS mentioned here what is the reason for having 8 of (Dual Common Cathode), is it to reduce heat dissipation or for those who want separate dual PS?
Thankyou
Hi,
In Pass F5T paper, power supply shows only 4 (Dual Common Cathode) diodes(MUR3020W).
In the PS mentioned here what is the reason for having 8 of (Dual Common Cathode), is it to reduce heat dissipation or for those who want separate dual PS?
Thankyou
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Hi all
Upon testing my v3 board unloaded (for an Aleph J) the inrush current is happily blowing time delay fuses up to 3.15 A.
I have a single thermistor across the AC lines as per the Pass PSU schematic for 240v.
Can anyone confirm that I have the thermistor in the correct position.
Is this typical of an unloaded PSU of this type?
Upon testing my v3 board unloaded (for an Aleph J) the inrush current is happily blowing time delay fuses up to 3.15 A.
I have a single thermistor across the AC lines as per the Pass PSU schematic for 240v.
Can anyone confirm that I have the thermistor in the correct position.
Is this typical of an unloaded PSU of this type?
The Power Thermistor should be in the primary feed.
It is an added resistance that limits the current during start up when the transformer has not yet got up to AC flux field.
A Thermistor across the Live to Neutral lines will bypass the transformer and blow the fuse every time !
Have you powered on your fuse blowing contraption via a Mains Bulb Tester?
The Bulb will turn ON if you are drawing excessive current. And save the fuse.
It is an added resistance that limits the current during start up when the transformer has not yet got up to AC flux field.
A Thermistor across the Live to Neutral lines will bypass the transformer and blow the fuse every time !
Have you powered on your fuse blowing contraption via a Mains Bulb Tester?
The Bulb will turn ON if you are drawing excessive current. And save the fuse.
No, a Power Thermistor in EITHER the Live line to the transformer OR the Neutral line to the transformer.
Which Power Thermistor are you using?
What is it's cold resistance?
The cold resistance is the first that limits the start up current. As it heats up that resistance falls to become a warm resistance. It probably never runs hot.
The CL60 has a cold resistance that suits US 110/120Vac transformers.
The CL60 does not suit 220/240Vac EU transformers.
In my view you need >>10ohms to be an effective current limiter on 240Vac in the UK.
10ohms in series with an OFF transformer will pass nearly 25Aac (35Apk) during the first cycle of mains and will certainly blow a T3.1A fuse.
A 3.1A fuse is suitable for a 700VA 230Vac transformer
Which Power Thermistor are you using?
What is it's cold resistance?
The cold resistance is the first that limits the start up current. As it heats up that resistance falls to become a warm resistance. It probably never runs hot.
The CL60 has a cold resistance that suits US 110/120Vac transformers.
The CL60 does not suit 220/240Vac EU transformers.
In my view you need >>10ohms to be an effective current limiter on 240Vac in the UK.
10ohms in series with an OFF transformer will pass nearly 25Aac (35Apk) during the first cycle of mains and will certainly blow a T3.1A fuse.
A 3.1A fuse is suitable for a 700VA 230Vac transformer
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I strongly suggest you build one and use it to power on EVERY modified, or new, mains powered project.
For 240V, a single CL-60 is used, in series with the hot, on the firstwatt factory-built amps. (It's actually wired between the two primary windings, but I think that was more for convenience in the PSU pcb layout.)
Wire your CL-60 in series with the hot AC lead, and continue testing.
Indeed! Very good advice. It's saved more than a few project for me.
Wire your CL-60 in series with the hot AC lead, and continue testing.
Indeed! Very good advice. It's saved more than a few project for me.
Pass shows two CL60 in many of his published DIY designs.For 240V, a single CL-60 is used, in series with the hot, on the firstwatt factory-built amps. (It's actually wired between the two primary windings, but I think that was more for convenience in the PSU pcb layout.)
Wire your CL-60 in series with the hot AC lead, and continue testing.
Indeed! Very good advice. It's saved more than a few project for me.
One CL60 to each 110/120Vac winding of the dual primary transformer.
When these are series connected for 220/240Vac mains supply one still uses two CL60, one to each 110/120Vac primary winding.
But I am stating that two CL60 for a 240Vac mains supply only works for very large fuse ratings.
I suggest that a much higher resistance (than two CL60 connected in series) be adopted when more sensible fuse ratings are used on 240Vac mains supplies.
For a 1200VA transformer I would fit a soft start and a T5A fuse.
That 5A fuse allows a short term 10Aac to flow during start up and not rupture.
240Vac & 10Aac equates to 24ohms of resistance including the primary winding.
If you use a smaller transformer you should use a smaller fuse and a higher added resistance.
That 5A fuse allows a short term 10Aac to flow during start up and not rupture.
240Vac & 10Aac equates to 24ohms of resistance including the primary winding.
If you use a smaller transformer you should use a smaller fuse and a higher added resistance.