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# Timed on/off switch

H

#### Homer J Simpson

Jan 1, 1970
0
Another thing I might just want to throw out there is that I am also
looking for other ways of preforming this operation. Basically what I
want to happen is:

http://i83.photobucket.com/albums/j306/krelver/tattoogun.jpg

1. Electromagnet energizes
2. Electromagnet attracts permanent magnet
3. Electromagnet denergizes
3. Permanent magnet get pushed away by the spring

And all off this to repeat at about 1-3hz...

Using a 555 timer in a strobe light circuit is the best I can think of
at the moment.

Think of it this way: It's like a pendulum, if you give it a little impulse
when it's going forward it will keep swinging. But if the impulses are
random or out of sync with the swing it will work erratically or stop
altogether. That's why the impulses must be synced to the movements which an
external generator won't do.

K

#### [email protected]

Jan 1, 1970
0
You're right, that one would give the correct frequency... A few
questions: What is happening on the far right with the IRL3303, what
is with the 2 wires that go right through? And is the fifth pin on the
555 not being used?

J

#### John Fields

Jan 1, 1970
0
You're right, that one would give the correct frequency... A few
questions: What is happening on the far right with the IRL3303, what
is with the 2 wires that go right through? And is the fifth pin on the
555 not being used?

---
I've re posted the schematic below, with a correction: the IRL3303
is an "N" channel enhancement-mode MOSFET used to drive the solenoid
and it has a drain, a gate, and a source, not a collector, base, and
emitter as shown earlier. I don't know what you mean by the two
wires that go right through, since one end of the solenoid coil and
the anode of the diode are connected to the drain, pin 3 of the 555
is connected to the gate, and the source is grounded. Pin 5 is for
voltage control of the output frequency/period, and may be left
floating in your application.

..+12>--+--------------------------+--------------------+
.. | | |
.. | | +-------+
.. [1000] +---------+ | |K |
.. | 7|_ |8 | [DIODE] [COIL]
.. +------------O|D Vcc|--+ | |
.. | 6| _|4 | +-------+
.. [82K] +-----+--|TH R|O-+ IRL3303 |
.. | | | 2|__ |3 | \ D
.. +->[500K] +-O|TR OUT|--|-------------+----G
.. | | | GND | | |K S
.. +----+ +----+----+ +------+ | |
.. | 1| 555 |+ | [1N4744] |
.. [0.68µF] | [10µF][100nF] | |
.. | | | | | |
..GND>-------+-------------+-------+------+------+------+

K

#### [email protected]

Jan 1, 1970
0
You're right, that one would give the correct frequency... A few
questions: What is happening on the far right with the IRL3303, what
is with the 2 wires that go right through? And is the fifth pin on the
555 not being used?

---
I've re posted the schematic below, with a correction: the IRL3303
is an "N" channel enhancement-mode MOSFET used to drive the solenoid
and it has a drain, a gate, and a source, not a collector, base, and
emitter as shown earlier. I don't know what you mean by the two
wires that go right through, since one end of the solenoid coil and
the anode of the diode are connected to the drain, pin 3 of the 555
is connected to the gate, and the source is grounded. Pin 5 is for
voltage control of the output frequency/period, and may be left
floating in your application.

.+12>--+--------------------------+--------------------+
. | | |
. | | +-------+
. [1000] +---------+ | |K |
. | 7|_ |8 | [DIODE] [COIL]
. +------------O|D Vcc|--+ | |
. | 6| _|4 | +-------+
. [82K] +-----+--|TH R|O-+ IRL3303 |
. | | | 2|__ |3 | \ D
. +->[500K] +-O|TR OUT|--|-------------+----G
. | | | GND | | |K S
. +----+ +----+----+ +------+ | |
. | 1| 555 |+ | [1N4744] |
. [0.68µF] | [10µF][100nF] | |
. | | | | | |
.GND>-------+-------------+-------+------+------+------+

Thanks John... I am going to the local electronics store right now to
see if they have all the parts...

Do you know of any good online electronic (non-wholesale) distributors
that I could use that would ship to Canada?

-KV

R

#### Rich Grise

Jan 1, 1970
0
On Mar 22, 2:31 pm, "Greg Neill" <[email protected]> wrote:
Hi, this is my first post here, and I looking for either a component
or a circuit design for a special project I am doing.
Basically I need a component that switches the current running through
it on and off at a frequency of about 1-6 Hz.
I am fairly apt at soldering a general circuitry so any suggestions
would be great!
AC or DC current?
How much current?
What voltage?
What is your power supply voltage?
It will be a DC system running at 12V. It will be carrying close to 3
amps at max. It will be getting the power from a AC-DC converter
plugged into the wall. The load will be a electromagnet.

Something like this should do it for you:

+12 ---+------------------------------------+
|a |
[D1] |
| |
+----+--------+---+ |
| | | | +----+
| [1K] --------- | |
| | | 8 4 | | |
| +-----|7 | [100K] |
| | | | | |
| [33K] | 555 | | |-+s
| | | 3|---[330R]-+-,| STP12PF06
| +-----|6 | g||-+d
[100uF] | | | |
| +-----|2 | +----------+
| | | 5 1 | | |
| |+ --------- | |
| [10uF] | | [Electromagnet] [D2]
| | [.1uF] | | |a
| | | | | |
Gnd ---+----+--------+---+------------------+----------+

D1, D2 = 1N5404

With the values shown, the 555 should give you about
2 seconds on, 2 seconds off. Use a regular NE555, not
the cmos TLC555 version.

Ed

Thanks Ed, that actually looks a lot simpler than the one I planned on
using (and a bit more applicable)... A few questions: What type of
diodes should I use? and what components should I change if I wanted
to increase the frequency slightly?

The frequency will be inversely proportional to the value of the 10uF
cap at pins 2 & 6 - this is called the "timing cap". For example, a
4.7 uF would give about 1 sec. on and 1 off, a 2.2 would give you
about .5sec on and .5 sec off, and so on.
Could I add a rheostat anywhere?
2s on and 2s is a bit too slow, I think.

Yes, it's possible to use a rheostat, but I'm too lazy too look up the app
note on the best way to do that - I don't remember exactly how the
charge/discharge works, but the 1K and the 33K are used for that - I'd
also cut the cap to about 1 uF and change them to 10K and 330K, and
replace the 330K with a 100K pot connected as a rheostat, in series
with a 220K.

But the data sheet should have lots of example circuits - just google
for "555 data sheet".

I'm also thinking - I've seen an ordinary tattoo gun in operation,
and it sounded just like a standard buzzer, in the tens of Hz; so
you might have to keep an eye on the inductance of your solenoid
and various things like that.

Good Luck!
Rich

E

#### ehsjr

Jan 1, 1970
0
On Mar 22, 2:31 pm, "Greg Neill" <[email protected]> wrote:
Hi, this is my first post here, and I looking for either a component
or a circuit design for a special project I am doing.
Basically I need a component that switches the current running through
it on and off at a frequency of about 1-6 Hz.
I am fairly apt at soldering a general circuitry so any suggestions
would be great!
AC or DC current?
How much current?
What voltage?
What is your power supply voltage?
It will be a DC system running at 12V. It will be carrying close to 3
amps at max. It will be getting the power from a AC-DC converter
plugged into the wall. The load will be a electromagnet.

Something like this should do it for you:

+12 ---+------------------------------------+
|a |
[D1] |
| |
+----+--------+---+ |
| | | | +----+
| [1K] --------- | |
| | | 8 4 | | |
| +-----|7 | [100K] |
| | | | | |
| [33K] | 555 | | |-+s
| | | 3|---[330R]-+-,| STP12PF06
| +-----|6 | g||-+d
[100uF] | | | |
| +-----|2 | +----------+
| | | 5 1 | | |
| |+ --------- | |
| [10uF] | | [Electromagnet] [D2]
| | [.1uF] | | |a
| | | | | |
Gnd ---+----+--------+---+------------------+----------+

D1, D2 = 1N5404

With the values shown, the 555 should give you about
2 seconds on, 2 seconds off. Use a regular NE555, not
the cmos TLC555 version.

Ed

Thanks Ed, that actually looks a lot simpler than the one I planned on
using (and a bit more applicable)... A few questions: What type of
diodes should I use? and what components should I change if I wanted
to increase the frequency slightly? Could I add a rheostat anywhere?
2s on and 2s is a bit too slow, I think.

When I replied, the reply from John Fields was not
yet on my server, so I didn't see it. His circuit
gives you the ability to adjust the timing. On the
one I posted, change the 33K resistor to a 200K
pot to vary the timing. Diodes = 1N5404

John's circuit is better than mine, but I would
make 2 changes to it: add a diode and change the
10 uF to 100 uF. I'll show the change to add the
diode below, in a partial schematic. The remainder
is the same as John posted, except the 10uF cap
is changed to 100uF. The added diode is a 1N4148

..+12>--+-----------------------------------------------+
.. | |
.. [Diode] |
.. |k |
.. +--------------------------+ |
.. | | +-------+
.. [1000] +---------+ | |K |
.. | 7|_ |8 | [DIODE] [COIL]

The purpose is to stabilize the voltage to the 555 when the
solenoid fires.

Ed

H

#### Homer J Simpson

Jan 1, 1970
0
Do you know of any good online electronic (non-wholesale) distributors
that I could use that would ship to Canada?

For Canada, go to R P Electronics in Burnaby, BC. They ship world wide but
you'll avoid border fees.

http://www.rpelectronics.com/

J

#### John Fields

Jan 1, 1970
0
On 22 Mar 2007 17:02:58 -0700, [email protected] wrote:
Okay... I think I found the circuit I am going to try to assemble... I
am confident that I can do it:

---
Hmmm... What's wrong with the circuit I gave you?
You're right, that one would give the correct frequency... A few
questions: What is happening on the far right with the IRL3303, what
is with the 2 wires that go right through? And is the fifth pin on the
555 not being used?

---
I've re posted the schematic below, with a correction: the IRL3303
is an "N" channel enhancement-mode MOSFET used to drive the solenoid
and it has a drain, a gate, and a source, not a collector, base, and
emitter as shown earlier. I don't know what you mean by the two
wires that go right through, since one end of the solenoid coil and
the anode of the diode are connected to the drain, pin 3 of the 555
is connected to the gate, and the source is grounded. Pin 5 is for
voltage control of the output frequency/period, and may be left
floating in your application.

.+12>--+--------------------------+--------------------+
. | | |
. | | +-------+
. [1000] +---------+ | |K |
. | 7|_ |8 | [DIODE] [COIL]
. +------------O|D Vcc|--+ | |
. | 6| _|4 | +-------+
. [82K] +-----+--|TH R|O-+ IRL3303 |
. | | | 2|__ |3 | \ D
. +->[500K] +-O|TR OUT|--|-------------+----G
. | | | GND | | |K S
. +----+ +----+----+ +------+ | |
. | 1| 555 |+ | [1N4744] |
. [0.68µF] | [10µF][100nF] | |
. | | | | | |
.GND>-------+-------------+-------+------+------+------+

Thanks John... I am going to the local electronics store right now to
see if they have all the parts...

Do you know of any good online electronic (non-wholesale) distributors
that I could use that would ship to Canada?

---
I think Mouser:

http://www.mouser.com/index.cfm?handler=home

and Digi-Key:

http://www.digikey.com/

will.

BTW, I made an error by not accounting for the astable OFF time,
which resulted in the output frequency being twice as high as it
should be. The following shows the cap as what it should be, 1.2µF,
plus Ed's good suggestions are added.

..+12>--+-----------------------------------------------+
.. | |
.. [1N4148] |
.. |K |
.. +--------------------------+ |
.. | | +-------+
.. [1000] +---------+ | |K |
.. | 7|_ |8 | [DIODE] [COIL]
.. +------------O|D Vcc|--+ | |
.. | 6| _|4 | +-------+
.. [82K] +-----+--|TH R|O-+ IRL3303 |
.. | | | 2|__ |3 | \ D
.. +->[500K] +-O|TR OUT|--|-------------+----G
.. | | | GND | | | S
.. +----+ +----+----+ +------+ |K |
.. | 1| 555 |+ | [1N4744] |
.. [1.2µF] | [100µF][100nF] | |
.. | | | | | |
..GND>-------+-------------+-------+------+------+------+

K

#### [email protected]

Jan 1, 1970
0
On 23 Mar 2007 07:28:04 -0700, [email protected] wrote:
On 22 Mar 2007 17:02:58 -0700, [email protected] wrote:
Okay... I think I found the circuit I am going to try to assemble.... I
am confident that I can do it:
http://www.tkk.fi/Misc/Electronics/circuits/strobocontrol.html
---
Hmmm... What's wrong with the circuit I gave you?
--
JF
You're right, that one would give the correct frequency... A few
questions: What is happening on the far right with the IRL3303, what
is with the 2 wires that go right through? And is the fifth pin on the
555 not being used?
---
I've re posted the schematic below, with a correction: the IRL3303
is an "N" channel enhancement-mode MOSFET used to drive the solenoid
and it has a drain, a gate, and a source, not a collector, base, and
emitter as shown earlier. I don't know what you mean by the two
wires that go right through, since one end of the solenoid coil and
the anode of the diode are connected to the drain, pin 3 of the 555
is connected to the gate, and the source is grounded. Pin 5 is for
voltage control of the output frequency/period, and may be left
floating in your application.
.+12>--+--------------------------+--------------------+
. | | |
. | | +-------+
. [1000] +---------+ | |K |
. | 7|_ |8 | [DIODE] [COIL]
. +------------O|D Vcc|--+ | |
. | 6| _|4 | +-------+
. [82K] +-----+--|TH R|O-+ IRL3303 |
. | | | 2|__ |3 | \ D
. +->[500K] +-O|TR OUT|--|-------------+----G
. | | | GND | | |K S
. +----+ +----+----+ +------+ | |
. | 1| 555 |+ | [1N4744] |
. [0.68µF] | [10µF][100nF] | |
. | | | | | |
.GND>-------+-------------+-------+------+------+------+
Thanks John... I am going to the local electronics store right now to
see if they have all the parts...
Do you know of any good online electronic (non-wholesale) distributors
that I could use that would ship to Canada?

---
I think Mouser:

http://www.mouser.com/index.cfm?handler=home

and Digi-Key:

http://www.digikey.com/

will.

BTW, I made an error by not accounting for the astable OFF time,
which resulted in the output frequency being twice as high as it
should be. The following shows the cap as what it should be, 1.2µF,
plus Ed's good suggestions are added.

.+12>--+-----------------------------------------------+
. | |
. [1N4148] |
. |K |
. +--------------------------+ |
. | | +-------+
. [1000] +---------+ | |K |
. | 7|_ |8 | [DIODE] [COIL]
. +------------O|D Vcc|--+ | |
. | 6| _|4 | +-------+
. [82K] +-----+--|TH R|O-+ IRL3303 |
. | | | 2|__ |3 | \ D
. +->[500K] +-O|TR OUT|--|-------------+----G
. | | | GND | | | S
. +----+ +----+----+ +------+ |K |
. | 1| 555 |+ | [1N4744] |
. [1.2µF] | [100µF][100nF] | |
. | | | | | |
.GND>-------+-------------+-------+------+------+------+

One more questions (easy ones): What is with the 500k piece with 3
inputs? and the 1000 part, is that just a 1000 ohm resistor? I think I
am going to ship from mouser because then I can just buy 1 or 2 of the
parts I'll need rather than increments of 10.

B

#### bw

Jan 1, 1970
0
One more questions (easy ones): What is with the 500k piece with 3
inputs? and the 1000 part, is that just a 1000 ohm resistor? I think I
am going to ship from mouser because then I can just buy 1 or 2 of the
parts I'll need rather than increments of 10.- Hide quoted text -

The 500k is a potentiometer (variable resistor)

You will learn more by building John's custom design
but also consider that you might puchase a kit for $7 http://www.apogeekits.com/interval_timer_555.htm The kit will do exactly what you specified. It will run off a wall wart. Even if the timing range is not exactly what you need, the kit could be modified by changing only one part, the timing cap K #### [email protected] Jan 1, 1970 0 The 500k is a potentiometer (variable resistor) You will learn more by building John's custom design but also consider that you might puchase a kit for$7http://www.apogeekits.com/interval_timer_555.htm

The kit will do exactly what you specified. It will run off a wall
wart. Even if the timing range is not exactly what you need, the kit
could be modified by changing only one part, the timing cap

Sorry, I was away for the weekend...

I think I am going to try John's method. It seems more fun. I have
ordered the parts from mouser, and they should arrive sometime this
week. I'll post a follow up when I complete it, and I'll let you guys
know how it went. Thanks for all your guys' help!

-KV

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