♫♪ My little cheap Circlophone© ♫♪

Yes ca. 1V DC. the capacitor C2 (100µF) can be increased to measure a longer DC phase. But do not exceed 330µF please. Trimmer 100k can increase or decrease the delay. In my case I set it to 3 seconds so that the amplifier and the power supply can level themselves reasonably. BC639 can also be BD139. They are pin compatible.
 
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Hello,

The track width only plays a significant role if there is a ground plane below/above it.
ground plane is present below / above it. He cannot choose the distance
arbitrarily: it is limited by the minimum insulation distance (approx.
0.2 mm) and "closely adjacent" because of the total available area.
(costs money). The copper thickness is also not arbitrarily selectable
(18-70um) -> in practice, the capacitance of pairs of conductors on 2-layer layouts
layouts varies only insignificantly by 50pF/m.
But we are not only talking about capacities but also inductances, but honestly that would overload the discussion here. We are talking about an audible frequency band.
According to my examination, the layout seems to be HF-tight, which means no oscillations in the audible range. Fortunately, there is no "ground plane" in the layout.
But still, I'll give it more thought next time. I'm going to have a coffee now....
 
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My Circlophone pcb arrived today! :hbeat:
For parts my options are.....
Output tr- MJL21194/TIP35C
Driver tr- c4793/BD140(ST)
Small signal tr- BC546B & 556B(PH)
VAS tr- Sanyo c2911(Cob 3pf, 150mhz, to-126, linear Hfe)
Schottky diode- BAT86 & SR5100

Anyway i want to thank Mr.Elvee for this world class amplifier design! Thank you!

20220514_123948.jpg
 
Another user asked about a Circlophone stereo version with protection circuit complete on one board, are you interested in that too ?
I did that years ago for a German company, with central star grounding. But without power supply.
Thanks back !
Hi Oscar,

Apologies for a delayed reply

I do have a pair of boards made by Prasi, but I would really love a stereo version of the board ( 200mm wide ) such that the protection circuit is in the center with the amps on either side and a single transformer input with each amp having its own power supply ( rectifier and Caps. ).

Above was just a thought, I would be ok with what you described. I do have quite a bit of space in my eclosure ( in fabrication ) so a separate protection board can be used

Would it be possible for you to make a board that is solid-state (MOSFET) for speaker protection since relay could get fused due to high current
 
Ich denke, ich sollte dem Originalschema ohne Mod folgen, aber ich möchte trotzdem wissen, wie hoch die Toleranz dieses Kondensators ist. Oft verwenden wir dort 10-100pf npo parallel zum Rückkopplungswiderstand.
Jedenfalls habe ich bereits eine Bestellung für 27pf 50v cog mlcc aufgegeben (ich denke, die DC-Spezifikation ist dort irrelevant).
27pf is very ok.
 
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Elvee

Member
2006-09-08 2:04 pm
Dear Mr Elvee do you recommend use of 33-47 pf instead of 27pf for C4? i hve plenty of 47pf COG. Need your advice before i place an order.
33pF won't make any difference.
47pF will begin to decrease the bandwidth, but as you start from ~150kHz IIRC, you have some margin. Don't go to far into that direction though, because it will alter the loop gain at HF, which could lead to instabilities and oscillations
 
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Thank you Oscar and Mr Elvee. That's why i was reluctant to use 47pf there, because at the moment i don't have Scope & the knowledge to explore everything:shy:

As far as i understand Circlo works best with relatively slow (<4MHZ) output transistors so it's wise to use recommended values as i don't want to ruin high frequency performance. Btw i'll use 4.7pf between C&B of C2911(VAS) to prevent any possible oscillation.
 
I had enquiries in Germany about the interchangeability of the relays for my protection circuit.
I then took the trouble to find a relay that is pin compatible.
which is pin compatible. I found the relay with the type designation RW-SS-112D (Goodsky).
1. high switching current up to 15A in small size. (120VAC)
2. sugar-cube relay suitable for various applications.
3. UL, C-UL & TÜV safety standard approved.
4. UL Class F insulation available.
5. Highly adapt to harsh conditions with high
temperature and vibration.
6. halogen free series available.
7. Comply with RoHS and REACH regulations.
8. in accordance with IEC 60335-1 Glow Wire
requirements for home appliances.
Max. On/Off Switching:
Electrical ...............................6 Cycles per minute (this is more than sufficient).

The excitation coil only requires a current of approx. 30mA. For high power applications, such as switching inductive loads, the contact material AgSnO2 is suitable and is also recommended exclusively as a single contact. This relay has a single contact and is therefore ideally suited for switching amplifiers with approx. 150 Watt. The relay RW-SS-112D is pin compatible with the relay HF3FA12. Please note the large D at the end when ordering. The contact resistance is also within the usual range and is only 0.1 Ohm. This is fine!
Now I would like to answer ADITYA's question in post #2210.
Circlophone amplifier stereo on a PCB makes sense, but I would advise against including the power supply on the PCB. I will put the protection circuit on the PCB though. I didn't understand your question about MOSFET (protection circuit?). Sorry
What would make more sense for the circuit board? Left and right arrangement of the heat sink on the PCB ? So then it would be 2 pieces or one common heat sink, aligned as usual at the top in the longitudinal direction of the board ?
Many greetings
 
I had enquiries in Germany about the interchangeability of the relays for my protection circuit.
I then took the trouble to find a relay that is pin compatible.
which is pin compatible. I found the relay with the type designation RW-SS-112D (Goodsky).
1. high switching current up to 15A in small size. (120VAC)
2. sugar-cube relay suitable for various applications.
3. UL, C-UL & TÜV safety standard approved.
4. UL Class F insulation available.
5. Highly adapt to harsh conditions with high
temperature and vibration.
6. halogen free series available.
7. Comply with RoHS and REACH regulations.
8. in accordance with IEC 60335-1 Glow Wire
requirements for home appliances.
Max. On/Off Switching:
Electrical ...............................6 Cycles per minute (this is more than sufficient).

The excitation coil only requires a current of approx. 30mA. For high power applications, such as switching inductive loads, the contact material AgSnO2 is suitable and is also recommended exclusively as a single contact. This relay has a single contact and is therefore ideally suited for switching amplifiers with approx. 150 Watt. The relay RW-SS-112D is pin compatible with the relay HF3FA12. Please note the large D at the end when ordering. The contact resistance is also within the usual range and is only 0.1 Ohm. This is fine!
Now I would like to answer ADITYA's question in post #2210.
Circlophone amplifier stereo on a PCB makes sense, but I would advise against including the power supply on the PCB. I will put the protection circuit on the PCB though. I didn't understand your question about MOSFET (protection circuit?). Sorry
What would make more sense for the circuit board? Left and right arrangement of the heat sink on the PCB ? So then it would be 2 pieces or one common heat sink, aligned as usual at the top in the longitudinal direction of the board ?
Many greetings
Hi Oscar,

very informative input on the relays,

I will be comfortable with a board without the power supply as you mentioned

my intention is to use my 215mm x 75mm x 75mm heatsink for stereo. It’s 0.5 k/w for 100mm and is very hefty near about 2kg 😱.

currently I m using My Rev A (LM3886) on it.

Regarding the MOSFET question - I had seen some solid state speaker protection boards and wondered if you had made any or could build one.
 
Hi Oscar,

very informative input on the relays,

I will be comfortable with a board without the power supply as you mentioned

my intention is to use my 215mm x 75mm x 75mm heatsink for stereo. It’s 0.5 k/w for 100mm and is very hefty near about 2kg 😱.

currently I m using My Rev A (LM3886) on it.

Regarding the MOSFET question - I had seen some solid state speaker protection boards and wondered if you had made any or could build one.
Hello Aditya, Ok the solid state relays are a thing of their own, usually they are MOSFET controlled !
But now comes the problem, who guarantees that the Mosfet never, I stress never, fails and thus the full operating voltage of the protective circuit reaches the loudspeaker? And the cost-benefit expenditure is simply too great. Let's stay with the mechanical solution. I think that makes more sense, don't you ?
The heat sink you have specified will be sufficient without fan cooling for 2*95 Watt at 4R. More is not possible...

Translated with www.DeepL.com/Translator (free version)
 
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Hello Aditya, Ok the solid state relays are a thing of their own, usually they are MOSFET controlled !
But now comes the problem, who guarantees that the Mosfet never, I stress never, fails and thus the full operating voltage of the protective circuit reaches the loudspeaker? And the cost-benefit expenditure is simply too great. Let's stay with the mechanical solution. I think that makes more sense, don't you ?
The heat sink you have specified will be sufficient without fan cooling for 2*95 Watt at 4R. More is not possible...

Translated with www.DeepL.com/Translator (free version)
Cool I do not intend to go beyond 30watt or in a happy state 50 watts into 8ohms. 😊

currently trying to figure my PGA2330 /11 board. And cabinet

awaiting your boards and I am using MJL21194 and vas 3019