Hi ZM
If implementing logic solution to control input relays, does logic also have to be programmed to activate 6th relay when single ended input is selected?…or is this handled somehow when a single ended input is activated?
Also, can you outline changes to PCB required to reverse polarity needed by relays so they can be controlled by logic?
If implementing logic solution to control input relays, does logic also have to be programmed to activate 6th relay when single ended input is selected?…or is this handled somehow when a single ended input is activated?
Also, can you outline changes to PCB required to reverse polarity needed by relays so they can be controlled by logic?
see - original schematic is with plain dumb rotary switch
switch is dumb, so I did thinking instead - whichever of 5 inputs is dedicated for SE, all you need is to bridge input pads 1 & 3, and to solder corresponding diode, marked DI*
that diode exactly is taking care that K6 is getting juice to its coil, while cap in parallel (with series resistor) is taking care of K6 being energized slightly later than corresponding input relay, and being switched off slightly later
all that to avoid clicks in speakers - too many switches operating in same moment is never good
in short - electrically wise - your Logic circuit doesn't need to be any smarter than dumb rotary switch
yeah, it need to be Make Before Break , but that's code thing
switch is dumb, so I did thinking instead - whichever of 5 inputs is dedicated for SE, all you need is to bridge input pads 1 & 3, and to solder corresponding diode, marked DI*
that diode exactly is taking care that K6 is getting juice to its coil, while cap in parallel (with series resistor) is taking care of K6 being energized slightly later than corresponding input relay, and being switched off slightly later
all that to avoid clicks in speakers - too many switches operating in same moment is never good
in short - electrically wise - your Logic circuit doesn't need to be any smarter than dumb rotary switch
yeah, it need to be Make Before Break , but that's code thing
Hi, my kit arrived today. fantastic job guys. Many thanks for your commitment. At all levels. Keep the soldering iron hot.
Mats
Mats
When I was a wee little man, maybe 3 or 4 years old, I picked up the wrong side of a "screwdriver" my daddy was using while working on an old BSA, as he no doubt carried on the longstanding tradition of cursing Lucas electrics..... and grab it from proper side
Needless to say, I dropped it in surprise right away, and managed to hold my tears in until mommy came home.
Some years ago, I left the iron on the floor and forgot it. Some minutes later I put my knee on the hot tip...
Gaetano.
Gaetano.
I looked at this application note from Cinemag which compares HiNi (80% Ni), (50% Ni, 50% Steel), 100% Steel (maybe silicon steel?) cores for distortion.
https://cinemag.biz/application_notes/PDF/AN-104.pdf
It concludes that NiHi is superior. But they don't write what the last 20% is in this alloy. Can it be considered that it is steel?
They write that the high price tag of the HiNi transformers is because Nickel is expensive but price tag is about 100 USD pr. kg and the small transformer we use I guess not more than 5 USD Nickel raw material. Cobalt is a lot more expensive (about 30.000 USD pr. kg). Could the core be a NiCo core so last 20% is Cobalt? .....would a pure Cobalt core be fun?
https://cinemag.biz/application_notes/PDF/AN-104.pdf
It concludes that NiHi is superior. But they don't write what the last 20% is in this alloy. Can it be considered that it is steel?
They write that the high price tag of the HiNi transformers is because Nickel is expensive but price tag is about 100 USD pr. kg and the small transformer we use I guess not more than 5 USD Nickel raw material. Cobalt is a lot more expensive (about 30.000 USD pr. kg). Could the core be a NiCo core so last 20% is Cobalt? .....would a pure Cobalt core be fun?
If the core material is 80% Nickel and 20% Iron......this is called mu-metal?
Is Cinemag core mu-metal?
Is Cinemag core mu-metal?
It might be NiSi (nickel-silicon), which is what Electra-Print used to use in some of their line level transformers.
Ok, since they don't write it.......it may be something they keep for them self.....
This article is also interesting:
https://www.sowter.co.uk/pdf/GAVS.pdf
He writes a little about Nickel-Cobalt which they call "Permendur".........
This article is also interesting:
https://www.sowter.co.uk/pdf/GAVS.pdf
He writes a little about Nickel-Cobalt which they call "Permendur".........
Something else that needs to be changed is the relay coil voltage. I.e. 3V for 3.3V logic. I'll be using 5V logic and 5V relays (RY-5W-K) with gold contacts. So, remember to use the correct relays and also, don't connect the relay directly to the i/o pin of the Arduino. Instead, use a transistor to switch the relay because the Arduino pin won't be able to supply the current drawn by the relay coil - typically 100mA - 150mA. Arduino can safely supply only about 20mA.
I prefer having separate 24Vdc rail for relays - counting that these are asking for much lower current than 3V3 or 5V ones
and yes, that's exactly low side switch, (as I see it) normal way with logic
Thanks ZM. So, are you advising to stick with 24V relays and using a transistor to switch the relay? Would the BC547 be able to handle 24V, although at lower current?
I'm using the ESP32 which has 3.3V pins.
I'm using the ESP32 which has 3.3V pins.
of course that BC547 will endure 24Vdc, it's 50V, 100mA, 500mW part
and it'll see 24V only when closed, practically no current state
Fujitsu and similar relays with 24Vdc coil are drawing less than 10mA
esp32, as drawn, is dealing only with BC base
and it'll see 24V only when closed, practically no current state
Fujitsu and similar relays with 24Vdc coil are drawing less than 10mA
esp32, as drawn, is dealing only with BC base
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Thank you. Hopefully this will also help other Lazy Boyz who are considering using MCU's to switch the relays for muting, and switching inputs.
12V relays are also good using logic?…using separate supplies for logic and relays of course
Also, I’m curious…if 5V relays were used wouldn’t you have to change zener settings related to providing proper relay voltage?…does that affect anything else in the circuit?
Also, I’m curious…if 5V relays were used wouldn’t you have to change zener settings related to providing proper relay voltage?…does that affect anything else in the circuit?
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Where do you see 4k7 pot in BoM?
Edited - Good grief, sorry! Brain was in wrong place on another project. 5K should be fine. Sorry! 🙂
Edited - Good grief, sorry! Brain was in wrong place on another project. 5K should be fine. Sorry! 🙂