PCB: low voltage On-Off switch drives AC mains relay \ includes soft start .. H9KPXG

labjr

Member
2003-04-26 7:09 pm
MA
I ordered all the 3 chips direct from Ti with quick and cheap shipping. Maybe worth a look

Just the other day, I established an account at TI to order three CMOS logic chips I needed for a repair job. The package should arrive tomorrow. I'm glad they offer such a service since the parts are no longer carried by distributors. I know I won't be getting counterfeit parts from ebay or elsewhere.
 

jimk04

Member
Paid Member
2018-07-16 10:53 pm
North Notts
Just the other day, I established an account at TI
I set up an account a couple years ago when they had the 50% discount on the TPA3255EVM. That took forever to be delivered.....months....but was worth the wait and the discount.
I ordered 10 each of the chips at about £0.35 each and £5 delivery which took no time at all. Winner.!
 

Chiptech

Member
Paid Member
2019-04-16 5:16 pm
Tucson, AZ
I'm using the H9KPXG in my BA-3 preamp. Works like a champ.

I'd like to move to the Khozmo 64 steps relay-based ladder type attenuator with remote.

This set-up requires a 5VDC feed. I thought I could just use the 5Vdc from the board. But the Khozmo requires linear power supply, not SMPS. I'm trying to work out how to provide a linear power supply. I'm hoping I can use the Glassware LV-Regulator set to 5VDC which is currently sold out.

If that all holds together, I'm stumped as to how I feed or connect a 2nd transformer for the LV from the H9KPXG?

Also, I have three boards left from the order I placed last fall. Happy to pass on at cost. The boards work because I've built six of them and using them in my amps and preamps. Send me a PM.
 

Hicoco

Member
Paid Member
2018-02-14 4:54 pm
Provence
Thank you to Mark for sharing this design, So in the same spirit of customization I've taken this design to made 12V version with 2 relays, with a minor difference.

This is something that I really need to apply to a pair of APEX SR200 with a 625VA transformer.
I also need 12V for this project.


The CD40106 with 12V have a larger Hysteresis Voltage ( ~2,5V with 12V and 0.9V with 5V) so i readapted the R/C circuit to choose one of 3 possible delays (0.5, 1, or 2s). i can also adjust shorter or longer with the selector who have the possibility to have 2 or 3 resistances an parallel, I have to work and test little bit more to adapt better the values.

I'd like to get any comments on the PCB design before I send it to be manufactured. I should have spare PCBs if there's any interest in this version, and can share the Gerber files too.
I will do also an other version with 4 layers to double the high voltages tracks on the PCB.
Thanks
 

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Mark Johnson

Member
Paid Member
2011-05-27 3:27 pm
Silicon Valley
Have you double checked your PCB's minimum "creepage" and "clearance" for 230V mains safety? I'm by no means an expert myself.

For people who are thoroughly familiar with digital design and reading schematics of digital circuits, your incorrect use of "NAND" gate symbols for the CD4001, will be confusing and irritating. CD4001 is a quad NOR gate; drawing it as four NANDs misleads people. Post #1 of this thread shows the standard NOR gate symbol.
 

Hicoco

Member
Paid Member
2018-02-14 4:54 pm
Provence
Thanks to point me on this mistake i have updated the schematic with the right symbol, i saw also the Triac T1 have a wrong connection ( reversed). Yes i have enough clearance for 230V mains safety, i have 1mm and more .
 

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Mark Johnson

Member
Paid Member
2011-05-27 3:27 pm
Silicon Valley
Rod Elliott's (project 39) is a soft start circuit using an auxiliary transformer instead of an AC-to-DC SMPS. Which means: yes, it can be done. You'd have to create a new circuit board and include the diodes, filter capacitors, and transformer. I always liked the looks of those tiny blue cubes made by Block Transformers, maybe one of them might fit into your plans. They're available at Newark but not Mouser or DigiKey.

_
 

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sumeshak

Member
2014-04-29 1:29 pm
Rod Elliott's (project 39) is a soft start circuit using an auxiliary transformer instead of an AC-to-DC SMPS. Which means: yes, it can be done. You'd have to create a new circuit board and include the diodes, filter capacitors, and transformer. I always liked the looks of those tiny blue cubes made by Block Transformers, maybe one of them might fit into your plans. They're available at Newark but not Mouser or DigiKey.

_
Thank you,
I wish to build this project. Request to suggest any alternatives for TP2104 FET. This FET is not available here.
Regards,
Sumesh
 

Mark Johnson

Member
Paid Member
2011-05-27 3:27 pm
Silicon Valley
I'd suggest you investigate the ZVP series of thru-hole Pchannel MOSFETs from Diodes Inc. DigiKey lists more than 20 different part-numbers. ZVPs are famous for their extreme sensitivity to static / ESD, and many DIYers have inadvertently blown one up. Member / Advisor / Moderator 6L6 recommends that you "buy 5 when you only need 2", just to have spares handy. The Pearl 2 phonostage uses these parts, and it sounds fantastic. For 5V operation you'll get the largest safety margin with low-Vthreshold parts, and those seem to be the ones whose part number begins with "ZVP4". Lots of units in stock today at US DigiKey.
 

Mark Johnson

Member
Paid Member
2011-05-27 3:27 pm
Silicon Valley
There's no special reason, just inertia. Opamps are socketed so the builder can swap in different chips and listen for differences. Logic chips are socketed because builders often buy gray market logic parts and they fail more often than other semiconductors. Thru hole microcontrollers are socketed for reprogramming. DAC and ADC chips are socketed because they're expensive and you want to salvage them when discarding a board. None of those reasons are directly applicable to an opto-triac. But if you want to socket it anyway, go right ahead. Remember that it has 6 pins, not 8.
 

Mark Johnson

Member
Paid Member
2011-05-27 3:27 pm
Silicon Valley
BUILDER REQUEST: HELP ME INVENT A WAY TO OMIT THE PCHANNEL MOSFETS

I received a Private Message from someone who wants to copy the PO89ZB circuitry into a new project, except replace the Pchannel MOSFETs with all-bipolar substitute circuits. Since I believe that ten thousand heads are better than one, and the collective experience and wisdom of the Forum vastly exceeds that of any one member, I am moving that request out of Private Messaging and here into the public Forum. Would anyone like to answer this person's inquiry?

Is the active-high-input BJT circuit, equivalent to the active-low-input PMOS circuit?

If your answer is "No", do you have any improvements you can suggest?

{ start by calculating the base current(s) }

_
 

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