transformer 555 supply

S

steve

Guest
For the 555 timer, a transformer is used to run the circuit, instead
of the usual battery supply.

Although the transformer supplied the required 8-18 volts after
regulation, the circuit will not work with it.

However, the circuit works ok with the 9v battery only.

Since the ac supply is necessary, I would appreciate some answers
here.

Yours sincerely

Steve
 
On 2008-09-10, steve <kvsteve@gmail.com> wrote:
For the 555 timer, a transformer is used to run the circuit, instead
of the usual battery supply.

Although the transformer supplied the required 8-18 volts after
regulation, the circuit will not work with it.
constant DC?, does the voltage vary, does it drop below 6v often?

However, the circuit works ok with the 9v battery only.

Since the ac supply is necessary, I would appreciate some answers
here.
post a schematic (especially the supply, 555 circuit, and
some indication of the load)

Bye.
Jasen
 
On Wed, 10 Sep 2008 01:58:32 -0700 (PDT), steve <kvsteve@gmail.com>
wrote:

For the 555 timer, a transformer is used to run the circuit, instead
of the usual battery supply.

Although the transformer supplied the required 8-18 volts after
regulation, the circuit will not work with it.

However, the circuit works ok with the 9v battery only.

Since the ac supply is necessary, I would appreciate some answers
here.
---
Transformer?

Schematic?

JF
 
On Wed, 10 Sep 2008 06:29:08 -0700 (PDT),
"extremesoundandlight@yahoo.com" <extremesoundandlight@yahoo.com> wrote:

On Sep 10, 6:00 am, John Fields <jfie...@austininstruments.com> wrote:
On Wed, 10 Sep 2008 01:58:32 -0700 (PDT), steve <kvst...@gmail.com
wrote:

For the 555 timer, a transformer is used to run the circuit, instead
of the usual battery supply.

Although the transformer supplied the required 8-18 volts after
regulation, the circuit will not work with it.

However, the circuit works ok with the 9v battery only.

Since the ac supply is necessary, I would appreciate some answers
here.

---
Transformer?

Schematic?

JF

what’s the current draw on you secondary on your transformer and what
is a 555 timer, they probably use a transformer because 9v b+ is not
efficient to supply current over .5 milliamps and their would have to
be some form of half wave rectification to convert to DC current
transformers are much more efficient because the transformer passes as
much current ether step up or step down as the circuit requires.
---
news:ubnfc45b5aoivlee9g9vb4rne4e5sgj54o@4ax.com

JF
 
On Sep 10, 6:00 am, John Fields <jfie...@austininstruments.com> wrote:
On Wed, 10 Sep 2008 01:58:32 -0700 (PDT), steve <kvst...@gmail.com
wrote:

For the 555 timer, a transformer is used to run the circuit, instead
of the usual battery supply.

Although the transformer supplied the required 8-18 volts after
regulation, the circuit will not work with it.

However, the circuit works ok with the 9v battery only.

Since the ac supply is necessary, I would appreciate some answers
here.

---
Transformer?

Schematic?

JF
what’s the current draw on you secondary on your transformer and what
is a 555 timer, they probably use a transformer because 9v b+ is not
efficient to supply current over .5 milliamps and their would have to
be some form of half wave rectification to convert to DC current
transformers are much more efficient because the transformer passes as
much current ether step up or step down as the circuit requires.
 
On Sep 10, 4:01 pm, Jasen Betts <ja...@xnet.co.nz> wrote:
On 2008-09-10, steve <kvst...@gmail.com> wrote:

For the 555 timer, a transformer is used to run the circuit, instead
of the usual battery supply.

Although the transformer supplied the required 8-18 volts after
regulation, the circuit will not work with it.

constant DC?, does the voltage vary, does it drop below 6v often?

However, the circuit works ok with the 9v battery only.

Since the ac supply is necessary, I would appreciate some answers
here.

post a schematic (especially the supply, 555 circuit, and
some indication of the load)

Bye.
   Jasen



The rectified voltage does not vary, but is constant at the required
15 v.

This is due to prior rectification with a couple of diodes and caps
(1000 to 5000 uF).

Dc is sufficient to run the circuit ok, as provided by the 9 v
battery.

Steve.
 
On Sat, 13 Sep 2008 08:17:49 -0700 (PDT), steve <kvsteve@gmail.com>
wrote:

On Sep 10, 4:01 pm, Jasen Betts <ja...@xnet.co.nz> wrote:
On 2008-09-10, steve <kvst...@gmail.com> wrote:

For the 555 timer, a transformer is used to run the circuit, instead
of the usual battery supply.

Although the transformer supplied the required 8-18 volts after
regulation, the circuit will not work with it.

constant DC?, does the voltage vary, does it drop below 6v often?

However, the circuit works ok with the 9v battery only.

Since the ac supply is necessary, I would appreciate some answers
here.

post a schematic (especially the supply, 555 circuit, and
some indication of the load)

Bye.
   Jasen




The rectified voltage does not vary, but is constant at the required
15 v.

This is due to prior rectification with a couple of diodes and caps
(1000 to 5000 uF).

Dc is sufficient to run the circuit ok, as provided by the 9 v
battery.
---
Got a schematic of the circuit you can post somewhere?

JF
 
On Sep 13, 11:36 pm, John Fields <jfie...@austininstruments.com>
wrote:
On Sat, 13 Sep 2008 08:17:49 -0700 (PDT), steve <kvst...@gmail.com
wrote:





On Sep 10, 4:01 pm, Jasen Betts <ja...@xnet.co.nz> wrote:
On 2008-09-10, steve <kvst...@gmail.com> wrote:

For the 555 timer, a transformer is used to run the circuit, instead
of the usual battery supply.

Although the transformer supplied the required 8-18 volts after
regulation, the circuit will not work with it.

constant DC?, does the voltage vary, does it drop below 6v often?

However, the circuit works ok with the 9v battery only.

Since the ac supply is necessary, I would appreciate some answers
here.

post a schematic (especially the supply, 555 circuit, and
some indication of the load)

Bye.
   Jasen

The rectified voltage does not vary, but is constant at the required
15 v.

This is due to prior rectification with a couple of diodes and caps
(1000 to 5000 uF).

Dc is sufficient to run the circuit ok, as provided by the 9 v
battery.

---
Got a schematic of the circuit you can post somewhere?

JF- Hide quoted text -

- Show quoted text -
I have difficulty designing the circuit drawing in the gmail format
here.

If somebody could refer to a free site, i'll put the schematic in the
jpg/gif image.

Steve
 
steve wrote:

<snip>

- Show quoted text -


I have difficulty designing the circuit drawing in the gmail format
here.

If somebody could refer to a free site, i'll put the schematic in the
jpg/gif image.

Steve
Maybe Photobucket?

http://photobucket.com/
 
On Tue, 23 Sep 2008 07:29:28 -0700 (PDT), steve <kvsteve@gmail.com>
wrote:

On Sep 15, 10:32 pm, ehsjr <eh...@NOSPAMverizon.net> wrote:
steve wrote:

snip

- Show quoted text -

I have difficulty designing the circuit drawing in the gmail format
here.

If somebody could refer to a free site, i'll put the schematic in the
jpg/gif image.

Steve

Maybe Photobucket?

http://photobucket.com/


I have posted the schematic at
http://i401.photobucket.com/albums/pp94/steve0046/supplycircuit.gif

Please see.

Steve.
---
The top circuit is fine, and can be drawn in ASCII like this: (View in
Courier)


+----+
240AC>---+ +--|~ +|-----+----->VOUT
P||S | | |+
R||E | | [4700ľF]
I||C | | |
240AC>---+ +--|~ -|-----+----->GND
+----+


The bottom circuit won't work because the transformer needs a center tap
which needs to be grounded, like this:


240AC>---+ +----[DIODE>]--+
P||S |
R||E--+-[-BFC+]---+
I||C | |
240AC>---+ +--|-[DIODE>]--+--->VOUT
|
+--------------->GND

I don't recall what your problem was; can you describe it again, please?

JF
 
On Sep 15, 10:32 pm, ehsjr <eh...@NOSPAMverizon.net> wrote:
steve wrote:

snip

- Show quoted text -

I have difficulty designing the circuit drawing in the gmail format
here.

If somebody could refer to a free site, i'll put the schematic in the
jpg/gif image.

Steve

Maybe Photobucket?

http://photobucket.com/

I have posted the schematic at
http://i401.photobucket.com/albums/pp94/steve0046/supplycircuit.gif

Please see.

Steve.
 
steve wrote:
On Sep 15, 10:32 pm, ehsjr <eh...@NOSPAMverizon.net> wrote:

steve wrote:

snip

- Show quoted text -

I have difficulty designing the circuit drawing in the gmail format
here.

If somebody could refer to a free site, i'll put the schematic in the
jpg/gif image.

Steve

Maybe Photobucket?

http://photobucket.com/



I have posted the schematic at
http://i401.photobucket.com/albums/pp94/steve0046/supplycircuit.gif

Please see.

Steve.

The top one you drew will work, if you wired it correctly
and used proper components. The DC voltage it produces is
about 1.4 times the AC voltage produced at the secondary of
the transformer. That DC voltage will drop lower when a
load is connected to the supply.

You can regulate the DC voltage by adding a 3 leg regulator
chip like an LM7809. See the datasheet fig 7 page 22 at
http://www.fairchildsemi.com/ds/LM/LM7805.pdf

If that doesn't keep the voltage at a steady 9 volts, something
is wrong with your transformer (undersized or defective) or your
load draws excessive current.

Ed
 

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