Bugle power supply

[binspaul]

Hi,

I am working on a phono preamplifier project and I came across the Hagerman Bugle power supply. I would like to clarify the following doubts before moving further with the power supply.

1. The transformer required is center tapped or dual secondaries.
2. To obtain 15V for the regulators, how much output voltage should the transformer produce? Will 18V @ 1A is enough?

---
Best regards,
BP

http://www.hagtech.com/pdf/powersupply.pdf

 

[Samsara]

Hello.

Both transformers are ok because it's simplistic schematic, it must be at least 45VA.
For 1A you need MC7815 and MC7915 regulators, they need 17V input for 15V output.
They must have heatsink.

 

[binspaul]

Hi,

If I am using a dual secondary transformer, what should be the secondary voltages required? Will 18V with 1A for each secondaries enough? Or should I go for a high values?

---
Best regards,
BP

 

[Samsara]

18VAC = 25VDC.
Each regulators accept 35V.
Even 2x15v 45VA transformer is enough.

 

[AndrewT]

Hi,

I am working on a phono preamplifier project and I came across the Hagerman Bugle power supply. I would like to clarify the following doubts before moving further with the power supply.

1. The transformer required is center tapped or dual secondaries.
2. To obtain 15V for the regulators, how much output voltage should the transformer produce? Will 18V @ 1A is enough?

---
Best regards,
BP

http://www.hagtech.com/pdf/powersupply.pdf

the schematic shows a single bridge rectifier and the transformer is shown with a centre tapped secondary.
You MUST use a centre tapped secondary.
However, yiou can convert a dual secondary to centre tapped by series connecting the two secondaries in phase.
If you don't know how to do that then ask.
But first Build a Mains Bulb Tester.

 

[AndrewT]

18Vac is too much for a regulated 15Vdc.
Use a 15Vac secondary for a regulated 15Vdc
At low current the 15Vac secondary will give 21Vdc to 23Vdc across the smoothing capacitors. This is plenty to avoid drop out of the 7815/7915 (or 317/337) regulators, even when the mains voltage drops to 210Vac.

A dual 15Vac transformer rated at 30VA has a maximum continuous AC current of 1Aac
After passing into a capacitor input filter the maximum continuous DC current is ~50% to 60% of that i.e. 500 to 600mAdc.
This level of continuous current will make the transformer hot.
Reduce you continuous demand by half, i.e. <300mAdc to operate cool.
For intermittent DC current, the transformer can supply much more demanding loads.

 

[Samsara]

the schematic shows a single bridge rectifier and the transformer is shown with a centre tapped secondary.

It show and use dual secondary transformer.

As shown in schematic, each secondary winding direction are indicated with black point.

Secondaries of your transformer are 0 - 18 , 0 - 18 .
The wires 0 from one secondary must be connected to the wire 18 of the other secondary = GND.

 

[AndrewT]

It show and use dual secondary transformer.

.......

I see a centre tap connected to a GND symbol.

 

[Samsara]

Open the pdf.

 

[AndrewT]

Open the pdf.

the sch in post1 is the same as in the .pdf
Both show a centre tapped secondary and both show this connected to the ground symbol.
You are wasting our time.

 

[Samsara]

In fact there's 4 windings, 2 primaries and 2 secondaries.
Both are connected in serie.

 

[binspaul]

Hi,

The transformer should be a center tapped one with values (15-0-15). The final values should be considered based on the primary voltage and the regulator IC values.

---
Best regards,
BP

 

[binspaul]

Hi,

I was planning to use the bugle power supply to drive my B1 buffer pre amplifier board. The bugle power supply regulators used are 7824. But when the buffer board is connected, the 10R resistor in the power supply board blows off. What should be the reason? Without the preamplifier board connected, I am getting a stable 24V output.

Best regards,
BP

 

[peranders]

You will need a very small power supply since you want to supply only six opamps. I think 100 mA is more than you'll need. I have a small pcb for this consisting of LM317/337 and two small transformers.

 

[binspaul]

Hi,

I am having the bugle power supply with me and it is able to provide 100mA of current. The bugle features are:

• Clean, regulated +/-15Vdc outputs
• 0mA to 100mA output current
• Toroidal transformer
• Compact footprint
• 115Vac or 230Vac

But my issue is that the 10R resistor in the power supply board is getting blown up when the amplifier board is connected. What may be the cause for this?

Is the preamplifier drawing more current during bootup or a short in the board? I checked the board for continuity using multimeter and was unable to find any.

Best regards,
BP

 

[peranders]

How big is the resistor in wattage? How long time does it take to have blue smoke? How much current should your amp consume? Is it Bugle with six opamps? Type of opamps?

 

[binspaul]

Hello,

1. How big is the resistor in wattage?

The burnt out resistor is 500mW 100R metal film.

2. How long time does it take to have blue smoke?

This takes 2-3 seconds only.

3. How much current should your amp consume?

As per the B1 specification, the amp should take only 0.02A of current.

4. Is it Bugle with six opamps? Type of opamps?

I am confused. Please clarify. The issue is with Hagerman Bugle power supply, not with Bugle amplifier. The link to the power supply document is: http://www.hagtech.com/pdf/powersupply.pdf

Best regards,
BP

 

[Dennis Hui]

What B1 schematics are you using? The original B1 does not use a bipolar supply.

 

[JMFahey]

Dear binspaul, you are incredibly inconsistent in the data you supply, it´s IMPOSSIBLE to answer if you keep changing things all the time.

1) up to post#12, we were talking a +/-15V supply, fed from a 18+18V transformer (originally), switched to 15+15V in post #12 .
Then without explanation you switch from +/-15V rails to +/-24V
That alone invalidates all earlier calculations and answers

Even worse: by rising regulator voltage (24V) and lowering transformer voltage (15VAC means meager 21V peak/raw rail voltage) makes their work IMPOSSIBLE.
Do you realize that?

Hello,

1. How big is the resistor in wattage?

The burnt out resistor is 500mW 100R metal film.

Hey, earlier you said it was

the 10R resistor

PLEASE decide on one value and stick to it.

2. How long time does it take to have blue smoke?

This takes 2-3 seconds only.

3. How much current should your amp consume?

As per the B1 specification, the amp should take only 0.02A of current.

Then you have a shorted preamp.

4. Is it Bugle with six opamps? Type of opamps?

I am confused. Please clarify. The issue is with Hagerman Bugle power supply, not with Bugle amplifier.

If the amplifier shorts and burns the Power Supply then you DO have an issue with the Amplifier.

 

[peranders]

I must admit that I'm also confused since the thread started with "I am working on a phono preamplifier project". No it's the B1...