I use a dorm room style hot plate and an aluminum frypan. Not exact one but similar. The lower medium-low setting is about right. Use an IR thermometer to check temps. The low temp paste works real well and I set the pan for 160C. A variac is a great idea. Heat from the bottom and local hot air at 340C from the pencil on top.
https://a.co/d/7b0d9eL
https://a.co/d/7b0d9eL
For me it's to control temp of the hot plate I use, it's just a 300w max heating element that plugs directly into an AC source. I found that setting it around maybe 95VAC output gets me just the right temp for Chip Quik SMD291AX10T5
The cheap hot plate/variac idea is fantastic. I've been meaning to pick up a variac and this seals the deal.
@Algar_emi
If you want a pcb. you could buy this one. https://www.etsy.com/listing/769363...solid-state?ref=hp_active-mission-recs-rv-1-1
If you want a pcb. you could buy this one. https://www.etsy.com/listing/769363...solid-state?ref=hp_active-mission-recs-rv-1-1
That sounds consistent with the design. On power up connection is made via the triac and the NTC devices. The initial current surge is moderated by the NTC's. After about 2 seconds the MOSFETs engage and short out across the NTC and triac.
Yes, I was going to say what Jhofland said. Unless there is a load that draws a lot of current, the voltage will measure high when the triac turns on - immediately. Looks like your SFP is working as expected.
Yes it immediately plays but the current in rush is limited by the three NTCs in series. This prevents the mechanical and thermal stresses of a high current pulse hitting the trafo windings and other components. It’s different than an anti-pop turn on “mute” function. That requires an SSR at the speaker output with a delay - and you get that if you use my speaker protect SSR.
There is another type of PSU that has a soft start and that’s a capacitance multiplier with a topology similar to the one in this thread:
https://www.diyaudio.com/community/threads/jumas-easy-peasy-capacitance-multiplier.297921/
it has a slow 45 second long ramp up. At first there won’t be any sound until the voltage reaches a critical level where the amp plays music.
There is another type of PSU that has a soft start and that’s a capacitance multiplier with a topology similar to the one in this thread:
https://www.diyaudio.com/community/threads/jumas-easy-peasy-capacitance-multiplier.297921/
it has a slow 45 second long ramp up. At first there won’t be any sound until the voltage reaches a critical level where the amp plays music.
Good evening.
I am slowly progressing with my amp built.
Time to check if I have soldered soft start correctly.
Can anyone please confirm all is good so I can power it up ?
Thanks
I am slowly progressing with my amp built.
Time to check if I have soldered soft start correctly.
Can anyone please confirm all is good so I can power it up ?
Thanks
Looks good. Note that without a load, there will be a few volts after the triac when in the off state. But that’s normal.
