question

[HF_ATL]

Let's suppose I buy a receiver that has the following information:

- Voltage: 7-12V DC (positive center pin)
- Output Current: 245 mA

but I have a transformer that has 12v DC output (regulated between 1.5 an
12V) and 500ma, 6VA max, Input 230v-50hz 12.5W. Can I use it to power th
receiver safely?


Thanks

 

[Tom Biasi]

"HF_ATL" <concorde93@gmail.com> wrote in message
news:sOSdnRxOLoMvWszW4p2dnAA@giganews.com...

Let's suppose I buy a receiver that has the following information:

- Voltage: 7-12V DC (positive center pin)
- Output Current: 245 mA

but I have a transformer that has 12v DC output (regulated between 1.5 and
12V) and 500ma, 6VA max, Input 230v-50hz 12.5W. Can I use it to power the
receiver safely?


Thanks


Yes. Your spec is 12V, you have that at 245 mA you have better.

Tom

 

[Jamie]

HF_ATL wrote:

Let's suppose I buy a receiver that has the following information:

- Voltage: 7-12V DC (positive center pin)
- Output Current: 245 mA

but I have a transformer that has 12v DC output (regulated between 1.5 and
12V) and 500ma, 6VA max, Input 230v-50hz 12.5W. Can I use it to power the
receiver safely?


Thanks


Yes.

Actually, you're right on target.

Its good to operate at 50% capabilities.

 

[HF_ATL]

HF_ATL wrote:
Let's suppose I buy a receiver that has the following information:

- Voltage: 7-12V DC (positive center pin)
- Output Current: 245 mA

but I have a transformer that has 12v DC output (regulated between 1.
and
12V) and 500ma, 6VA max, Input 230v-50hz 12.5W. Can I use it to powe
the
receiver safely?


Thanks


Yes.

Actually, you're right on target.

Its good to operate at 50% capabilities.

So it means that the transformer gives 500ma maximum but if the receive
only needs 245ma then only 245ma will be drained by the transformer
right?

By the way, it's better to use 9v in the transformer? Since in this case
have 33,33% and 22,22% respectively for upper and lower voltage limit o
operation of the receiver (7-12V dc)?

Thanks for your answers!

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[krw]

On Sat, 16 Jan 2010 09:47:12 -0600, "HF_ATL"
<concorde93@n_o_s_p_a_m.gmail.com> wrote:

HF_ATL wrote:
Let's suppose I buy a receiver that has the following information:

- Voltage: 7-12V DC (positive center pin)
- Output Current: 245 mA

but I have a transformer that has 12v DC output (regulated between 1.5
and
12V) and 500ma, 6VA max, Input 230v-50hz 12.5W. Can I use it to power
the
receiver safely?


Thanks


Yes.

Actually, you're right on target.

Its good to operate at 50% capabilities.




So it means that the transformer gives 500ma maximum but if the receiver
only needs 245ma then only 245ma will be drained by the transformer,
right?

Where did the 245mA number come from?

By the way, it's better to use 9v in the transformer? Since in this case I
have 33,33% and 22,22% respectively for upper and lower voltage limit of
operation of the receiver (7-12V dc)?

Not necessarily. At the lower voltage the current will usually be
higher. That's why I asked were the 245mA came from. Three digit
precision indicates that it's not a "spec" number, rather something
measured (as a side note, therefore a "nominal" number). More
information please.

Thanks for your answers!

---------------------------------------
This message was sent using the sci.electronics.basics web interface on
http://www.Electronics-Related.com

Another Usenet free-loader.

 

[Tom Biasi]

"HF_ATL" <concorde93@n_o_s_p_a_m.gmail.com> wrote in message
news:LcWdnRbmd6UdQszWnZ2dnUVZ_qWdnZ2d@giganews.com...

HF_ATL wrote:
Let's suppose I buy a receiver that has the following information:

- Voltage: 7-12V DC (positive center pin)
- Output Current: 245 mA

but I have a transformer that has 12v DC output (regulated between 1.5
and
12V) and 500ma, 6VA max, Input 230v-50hz 12.5W. Can I use it to power
the
receiver safely?


Thanks


Yes.

Actually, you're right on target.

Its good to operate at 50% capabilities.




So it means that the transformer gives 500ma maximum but if the receiver
only needs 245ma then only 245ma will be drained by the transformer,
right?

By the way, it's better to use 9v in the transformer? Since in this case I
have 33,33% and 22,22% respectively for upper and lower voltage limit of
operation of the receiver (7-12V dc)?

Thanks for your answers!

Your receiver will draw the current necessary from your supply. You have a

good margine of safety.
The spec of 7-12 volts indicates that the receiver has it's own regulator.
Without seeing the circuit I don't know if it would be better to use 9
volts. Even it would, it would matter very little in this case.

Tom

 

[John Fields]

On Sat, 16 Jan 2010 08:05:38 -0600, "HF_ATL" <concorde93@gmail.com>
wrote:

Let's suppose I buy a receiver that has the following information:

- Voltage: 7-12V DC (positive center pin)
- Output Current: 245 mA

but I have a transformer that has 12v DC output (regulated between 1.5 and
12V) and 500ma, 6VA max, Input 230v-50hz 12.5W. Can I use it to power the
receiver safely?

---
This is sci.electronics.basics so, since you've made a few errors which
no one has addressed yet, let's correct them:

1. A receiver doesn't usually have an output current specification, so
what you probably mean is that it's rated for 7 to 12VDC in at 245mA
max, yes?

2. Transformers don't have DC outputs, so what you're referring to is an
AC to DC converter with a regulated output adjustable from 1.5 to
12VDC at 500mA max.

3. It appears you have the input and output spec's somewhat scrambled in
that AC inputs are rated in volt-amperes (VA) instead of watts, and
output power is rated in watts (W) instead of VA.

Such being the case, it appears that your supply requires an input of
230V 50Hz at 12.5VA and can output from 1.5 to 12VDC at 6W max.

Notice that this output power can only be realized when the output is
set at 12VDC, since with an output voltage >= 1.5V and <12V, the
product of voltage and current, which is power, will always be less
than 6 watts.

All that aside, since your supply can deliver 12VDC at 500mA and your
receiver only needs 245mA at 12V, it'll work fine with the supply set at
12V, as other posters have stated.


JF

 

[Paul E. Schoen]

"John Fields" <jfields@austininstruments.com> wrote in message
news:7014l5t0i3rpr56971d0na9l6krfbu1jeh@4ax.com...

On Sat, 16 Jan 2010 08:05:38 -0600, "HF_ATL" <concorde93@gmail.com
wrote:

Let's suppose I buy a receiver that has the following information:

- Voltage: 7-12V DC (positive center pin)
- Output Current: 245 mA

but I have a transformer that has 12v DC output (regulated between 1.5
and
12V) and 500ma, 6VA max, Input 230v-50hz 12.5W. Can I use it to power the
receiver safely?

---
This is sci.electronics.basics so, since you've made a few errors which
no one has addressed yet, let's correct them:

1. A receiver doesn't usually have an output current specification, so
what you probably mean is that it's rated for 7 to 12VDC in at 245mA
max, yes?

2. Transformers don't have DC outputs, so what you're referring to is an
AC to DC converter with a regulated output adjustable from 1.5 to
12VDC at 500mA max.

3. It appears you have the input and output spec's somewhat scrambled in
that AC inputs are rated in volt-amperes (VA) instead of watts, and
output power is rated in watts (W) instead of VA.

Such being the case, it appears that your supply requires an input of
230V 50Hz at 12.5VA and can output from 1.5 to 12VDC at 6W max.

Notice that this output power can only be realized when the output is
set at 12VDC, since with an output voltage >= 1.5V and <12V, the
product of voltage and current, which is power, will always be less
than 6 watts.

All that aside, since your supply can deliver 12VDC at 500mA and your
receiver only needs 245mA at 12V, it'll work fine with the supply set at
12V, as other posters have stated.

If the adjustable supply is a switcher, or if it uses a selection of taps
on a transformer, AND if the receiver has a linear regulator which accepts
the 7-12 VDC, then better overall efficiency may be obtained by setting the
supply to a lower value. You save (12-9)*0.245 = 0.74 watts by using 9 VDC.

Go for the green energy star!

Paul

 

[HF_ATL]

"John Fields" <jfields@austininstruments.com> wrote in message
news:7014l5t0i3rpr56971d0na9l6krfbu1jeh@4ax.com...
On Sat, 16 Jan 2010 08:05:38 -0600, "HF_ATL" <concorde93@gmail.com
wrote:

Let's suppose I buy a receiver that has the following information:

- Voltage: 7-12V DC (positive center pin)
- Output Current: 245 mA

but I have a transformer that has 12v DC output (regulated between 1.5
and
12V) and 500ma, 6VA max, Input 230v-50hz 12.5W. Can I use it to powe
the
receiver safely?

---
This is sci.electronics.basics so, since you've made a few errors which
no one has addressed yet, let's correct them:

1. A receiver doesn't usually have an output current specification, so
what you probably mean is that it's rated for 7 to 12VDC in at 245mA
max, yes?

2. Transformers don't have DC outputs, so what you're referring to i
an
AC to DC converter with a regulated output adjustable from 1.5 to
12VDC at 500mA max.

3. It appears you have the input and output spec's somewhat scramble
in
that AC inputs are rated in volt-amperes (VA) instead of watts, and
output power is rated in watts (W) instead of VA.

Such being the case, it appears that your supply requires an input of
230V 50Hz at 12.5VA and can output from 1.5 to 12VDC at 6W max.

Notice that this output power can only be realized when the output is
set at 12VDC, since with an output voltage >= 1.5V and <12V, the
product of voltage and current, which is power, will always be less
than 6 watts.

All that aside, since your supply can deliver 12VDC at 500mA and your
receiver only needs 245mA at 12V, it'll work fine with the supply se
at
12V, as other posters have stated.

If the adjustable supply is a switcher, or if it uses a selection of tap

on a transformer, AND if the receiver has a linear regulator which accept

the 7-12 VDC, then better overall efficiency may be obtained by settin
the
supply to a lower value. You save (12-9)*0.245 = 0.74 watts by using
VDC.

Go for the green energy star!

Paul

Thanks all of you for the feedback. So, right now I have no doubts that
can use the power adapter.
This is the item I want to buy
http://alai.h3m.com/~s0350672/catalogo/product_info.php?products_id=441&osCsid=d32035323c73bc5e61f72e5430e3891f

Don't know if the receiver has a linear regulator or not, only know what'
described in the website.

Btw, for 72 euros considering a 200mw 1.2ghz transmitter + receiver, is
expensive set?

Thanks again!

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[Jasen Betts]

On 2010-01-16, HF_ATL <concorde93@gmail.com> wrote:

Let's suppose I buy a receiver that has the following information:

- Voltage: 7-12V DC (positive center pin)
- Output Current: 245 mA

but I have a transformer that has 12v DC output (regulated between 1.5 and
12V) and 500ma, 6VA max, Input 230v-50hz 12.5W. Can I use it to power the
receiver safely?

given that it's regulated yeah that'll work (as long as you get + on
the center pin)

If it's adjustable I'de b incluned to set it to 9V or 7.5V just for
extra safety.


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