Triac Circuit Not working right ?

S

Stacy

Guest
I have built a circuit based on. It uses a Triac and a Optoisolator 3031 to
turn power on.
http://www.uoguelph.ca/~antoon/gadgets/relays/relays.html Solid State Relay
by Tony Van Roon

I hope that someone can answer a few questions ( If you could be simple on
your explanation as anything involved with get me lost)

1. The circuit I thought is suppose to be a Latching circuit. That is, from
my understanding, you apply the 5vDC for a second and the 120 light will
turn on. When you remove the 5v DC the 120 Volt light stays on. This does
not work for me. The 120 Volt light stays on only when I keep the 5 v DC
applied. When I remove it the light goes out.

2. The circuit does not work when I have the .01uf capacitor connected as
shown in the schematic. That is, the light simply comes on and stays on.
This is regardless of the 5 v DC.

Can anyone help me to understand. Or perhaps if the circuit is wired up as
described its suppose to exibit these symptoms ?

It frustrates me as Im trying to learn that I think I have done all the
right things, but then it doesnt work.

Thanks
 
On Wed, 24 Nov 2004 09:16:05 -0600, "Stacy" <stacy@123.com> wrote:

I have built a circuit based on. It uses a Triac and a Optoisolator 3031 to
turn power on.
http://www.uoguelph.ca/~antoon/gadgets/relays/relays.html Solid State Relay
by Tony Van Roon

I hope that someone can answer a few questions ( If you could be simple on
your explanation as anything involved with get me lost)

1. The circuit I thought is suppose to be a Latching circuit. That is, from
my understanding, you apply the 5vDC for a second and the 120 light will
turn on. When you remove the 5v DC the 120 Volt light stays on. This does
not work for me. The 120 Volt light stays on only when I keep the 5 v DC
applied. When I remove it the light goes out.
Click to expand...
---
That's the way it's supposed to work. When you remove the 5V you are
no longer supplying current to the LED in the opto, which disconnects
the TRIAC's gate from its trigger source, the mains.
---

2. The circuit does not work when I have the .01uf capacitor connected as
shown in the schematic. That is, the light simply comes on and stays on.
This is regardless of the 5 v DC.
Click to expand...
---
Make sure you have the capacitor connected to the junction of R3 and
R4 _only_, and that the gate of the TRIAC is _only_ connected to R5
and IC1-4. The "hump" in the wire connecting C1 to R3 and R4 means
that it jumps the wire it's crossing, not that it's connected to it.
---

Can anyone help me to understand. Or perhaps if the circuit is wired up as
described its suppose to exibit these symptoms ?

It frustrates me as Im trying to learn that I think I have done all the
right things, but then it doesnt work.
Click to expand...
---
Not to worry; we (me, anyway) all learn by trial and error. :)

--
John Fields
 
"John Fields" <jfields@austininstruments.com> wrote in message
news:1nb9q0pcsajomc41481ubirig7k6qjhs1s@4ax.com...
On Wed, 24 Nov 2004 09:16:05 -0600, "Stacy" <stacy@123.com> wrote:

I have built a circuit based on. It uses a Triac and a Optoisolator 3031
to
turn power on.
http://www.uoguelph.ca/~antoon/gadgets/relays/relays.html Solid State
Relay
by Tony Van Roon

I hope that someone can answer a few questions ( If you could be simple
on
your explanation as anything involved with get me lost)

1. The circuit I thought is suppose to be a Latching circuit. That is,
from
my understanding, you apply the 5vDC for a second and the 120 light will
turn on. When you remove the 5v DC the 120 Volt light stays on. This does
not work for me. The 120 Volt light stays on only when I keep the 5 v DC
applied. When I remove it the light goes out.

---
That's the way it's supposed to work. When you remove the 5V you are
no longer supplying current to the LED in the opto, which disconnects
the TRIAC's gate from its trigger source, the mains.
---

2. The circuit does not work when I have the .01uf capacitor connected
as
shown in the schematic. That is, the light simply comes on and stays on.
This is regardless of the 5 v DC.

---
Make sure you have the capacitor connected to the junction of R3 and
R4 _only_, and that the gate of the TRIAC is _only_ connected to R5
and IC1-4. The "hump" in the wire connecting C1 to R3 and R4 means
that it jumps the wire it's crossing, not that it's connected to it.
---

Can anyone help me to understand. Or perhaps if the circuit is wired up
as
described its suppose to exibit these symptoms ?

It frustrates me as Im trying to learn that I think I have done all the
right things, but then it doesnt work.

---
Not to worry; we (me, anyway) all learn by trial and error. :)

--
John Fields
Click to expand...
Thanks John, I'm glad it works sorta the way it is suppose to. I think I
have read about 5 or 10 of similar circuits and some of them they call them
latching. I must have had that confused.

Yes the "hump" is NOT connected. -thanks.

When you say
Make sure you have the capacitor connected to the junction of R3 and
R4 _only_, and that the gate of the TRIAC is _only_ connected to R5
and IC1-4.
Click to expand...
I do have the Cap between R3 and R4. From there the cap is connected to a
common line that has the R5 / MT1 and load connected up to it. (bread
board).


4-------Gate
|
..01u R5 MT1
|______|_____|______(Load)__
 
Stacy wrote:
"John Fields" <jfields@austininstruments.com> wrote in message
news:1nb9q0pcsajomc41481ubirig7k6qjhs1s@4ax.com...

On Wed, 24 Nov 2004 09:16:05 -0600, "Stacy" <stacy@123.com> wrote:


I have built a circuit based on. It uses a Triac and a Optoisolator 3031

to

turn power on.
http://www.uoguelph.ca/~antoon/gadgets/relays/relays.html Solid State

Relay

by Tony Van Roon

I hope that someone can answer a few questions ( If you could be simple

on

your explanation as anything involved with get me lost)

1. The circuit I thought is suppose to be a Latching circuit. That is,

from

my understanding, you apply the 5vDC for a second and the 120 light will
turn on. When you remove the 5v DC the 120 Volt light stays on. This does
not work for me. The 120 Volt light stays on only when I keep the 5 v DC
applied. When I remove it the light goes out.

---
That's the way it's supposed to work. When you remove the 5V you are
no longer supplying current to the LED in the opto, which disconnects
the TRIAC's gate from its trigger source, the mains.
---


2. The circuit does not work when I have the .01uf capacitor connected

as

shown in the schematic. That is, the light simply comes on and stays on.
This is regardless of the 5 v DC.

---
Make sure you have the capacitor connected to the junction of R3 and
R4 _only_, and that the gate of the TRIAC is _only_ connected to R5
and IC1-4. The "hump" in the wire connecting C1 to R3 and R4 means
that it jumps the wire it's crossing, not that it's connected to it.
---


Can anyone help me to understand. Or perhaps if the circuit is wired up

as

described its suppose to exibit these symptoms ?

It frustrates me as Im trying to learn that I think I have done all the
right things, but then it doesnt work.

---
Not to worry; we (me, anyway) all learn by trial and error. :)

--
John Fields


Thanks John, I'm glad it works sorta the way it is suppose to. I think I
have read about 5 or 10 of similar circuits and some of them they call them
latching. I must have had that confused.

Yes the "hump" is NOT connected. -thanks.

When you say

Make sure you have the capacitor connected to the junction of R3 and
R4 _only_, and that the gate of the TRIAC is _only_ connected to R5
and IC1-4.


I do have the Cap between R3 and R4. From there the cap is connected to a
common line that has the R5 / MT1 and load connected up to it. (bread
board).


4-------Gate
|
.01u R5 MT1
|______|_____|______(Load)__
Click to expand...
Look at the datasheet for the MOC3010. There is a sample circuit which
could be better for powering a lamp.

<http://www.fairchildsemi.com/ds/MO/MOC3010-M.pdf>

See Figure 6.

--
Regards,
Robert Monsen

"Your Highness, I have no need of this hypothesis."
- Pierre Laplace (1749-1827), to Napoleon,
on why his works on celestial mechanics make no mention of God.
 
"John Fields" <jfields@austininstruments.com> wrote in message
news:kul9q0ht6dvo7cqt9co459uha6idr236o5@4ax.com...
On Wed, 24 Nov 2004 12:03:22 -0600, "Stacy" <stacy@123.com> wrote:


"John Fields" <jfields@austininstruments.com> wrote in message
news:1nb9q0pcsajomc41481ubirig7k6qjhs1s@4ax.com...
On Wed, 24 Nov 2004 09:16:05 -0600, "Stacy" <stacy@123.com> wrote:

I have built a circuit based on. It uses a Triac and a Optoisolator
3031
to
turn power on.
http://www.uoguelph.ca/~antoon/gadgets/relays/relays.html Solid State
Relay
by Tony Van Roon

I hope that someone can answer a few questions ( If you could be
simple
on
your explanation as anything involved with get me lost)

1. The circuit I thought is suppose to be a Latching circuit. That is,
from
my understanding, you apply the 5vDC for a second and the 120 light
will
turn on. When you remove the 5v DC the 120 Volt light stays on. This
does
not work for me. The 120 Volt light stays on only when I keep the 5 v
DC
applied. When I remove it the light goes out.

---
That's the way it's supposed to work. When you remove the 5V you are
no longer supplying current to the LED in the opto, which disconnects
the TRIAC's gate from its trigger source, the mains.
---

2. The circuit does not work when I have the .01uf capacitor
connected
as
shown in the schematic. That is, the light simply comes on and stays
on.
This is regardless of the 5 v DC.

---
Make sure you have the capacitor connected to the junction of R3 and
R4 _only_, and that the gate of the TRIAC is _only_ connected to R5
and IC1-4. The "hump" in the wire connecting C1 to R3 and R4 means
that it jumps the wire it's crossing, not that it's connected to it.
---

Can anyone help me to understand. Or perhaps if the circuit is wired
up
as
described its suppose to exibit these symptoms ?

It frustrates me as Im trying to learn that I think I have done all
the
right things, but then it doesnt work.

---
Not to worry; we (me, anyway) all learn by trial and error. :)

--
John Fields

Thanks John, I'm glad it works sorta the way it is suppose to. I think I
have read about 5 or 10 of similar circuits and some of them they call
them
latching. I must have had that confused.

Yes the "hump" is NOT connected. -thanks.

When you say
Make sure you have the capacitor connected to the junction of R3 and
R4 _only_, and that the gate of the TRIAC is _only_ connected to R5
and IC1-4.

I do have the Cap between R3 and R4. From there the cap is connected to a
common line that has the R5 / MT1 and load connected up to it. (bread
board).


4-------Gate
|
.01u R5 MT1
|______|_____|______(Load)__



---
For your circuit, if the load is an incandescent lamp there's no need
for the 2.2k or the 10k resistors or the capacitor, since what you
have is what's called a "static switch" and you have no need for phase
control.

I think van Roon was confused and wanted to use the 2.2k and the 0.1ľF
as a snubber. Take a look at

http://www.littelfuse.com/data/en/Application_Notes/AN1007.pdf

for some circuits that work.

--
John Fields
Click to expand...
Thanks I will do some experimenting with them.

Ive done a little reading and found this ..

To prevent sensitive gate devices from false triggering due to high rates of
rise of off state voltage, 1 kW resistor in parallel with a 10nF

capacitor may be fitted between gate and cathode (gate and terminal 1 for a
triac). This approach is less effective for standard gate

devices. In this case, the preferred option is to fit an RC snubber between
anode and cathode (T2 and T1 for a triac) to reduce the dVD/dt below

the critical value.


http://www.semiconductors.philips.com/acrobat_download/various/SC03_RATING_CHARS



I did read some other documents about snubbers before and wondered if this
was the problem.



So the questions I have is, When would the circuit that I started out with
work exactly as drawn. Is the schematic wrong ? Is it for electric motors
etc. That is, a non resistive load ?



I suppose the begging question which you can't answer is why would an
intelligent electronics person put a schematic out there when it does not
work ? Or at best is not really going to work on an ordinary Incandescent
Light Bulb which it describes as the load?


Regards.
 
Stacy wrote:
I suppose the begging question which you can't answer is why would an
intelligent electronics person put a schematic out there when it does not
work ? Or at best is not really going to work on an ordinary Incandescent
Light Bulb which it describes as the load?
Click to expand...
There are *lots* of circuits that don't work on various web pages. There
are also lots of circuits that work, but only marginally, with parts
that may have different specs than your part.

I'm guessing that Tony Van Roon tried the circuit out, and for the triac
he was using (which is probably different than the one you are using) it
worked fine. The amount of current required by his triac was possibly
less that that required by yours.

Another flaw with the 'van roon' circuit is that the circuit is powered
at line voltage when the lamp is disconnected. If you touch it after
you've unscrewed the bulb, you'll get shocked. Many circuits put the
load on the high side (the Line side, black wire or small hole on the
plug) for that reason. The center tap of the socket (which is hardest to
touch) should be at Line, and the screw part should be at Neutral. The
fuse should also be on the Line side, preferably before the lamp itself.

--
Regards,
Robert Monsen

"Your Highness, I have no need of this hypothesis."
- Pierre Laplace (1749-1827), to Napoleon,
on why his works on celestial mechanics make no mention of God.
 
"Robert Monsen" <rcsurname@comcast.net> wrote in message
news:8d6pd.455963$D%.181033@attbi_s51...
Stacy wrote:
"John Fields" <jfields@austininstruments.com> wrote in message
news:1nb9q0pcsajomc41481ubirig7k6qjhs1s@4ax.com...

On Wed, 24 Nov 2004 09:16:05 -0600, "Stacy" <stacy@123.com> wrote:


I have built a circuit based on. It uses a Triac and a Optoisolator
3031

to

turn power on.
http://www.uoguelph.ca/~antoon/gadgets/relays/relays.html Solid State

Relay

by Tony Van Roon

I hope that someone can answer a few questions ( If you could be simple

on

your explanation as anything involved with get me lost)

1. The circuit I thought is suppose to be a Latching circuit. That is,

from

my understanding, you apply the 5vDC for a second and the 120 light
will
turn on. When you remove the 5v DC the 120 Volt light stays on. This
does
not work for me. The 120 Volt light stays on only when I keep the 5 v
DC
applied. When I remove it the light goes out.

---
That's the way it's supposed to work. When you remove the 5V you are
no longer supplying current to the LED in the opto, which disconnects
the TRIAC's gate from its trigger source, the mains.
---


2. The circuit does not work when I have the .01uf capacitor connected

as

shown in the schematic. That is, the light simply comes on and stays
on.
This is regardless of the 5 v DC.

---
Make sure you have the capacitor connected to the junction of R3 and
R4 _only_, and that the gate of the TRIAC is _only_ connected to R5
and IC1-4. The "hump" in the wire connecting C1 to R3 and R4 means
that it jumps the wire it's crossing, not that it's connected to it.
---


Can anyone help me to understand. Or perhaps if the circuit is wired up

as

described its suppose to exibit these symptoms ?

It frustrates me as Im trying to learn that I think I have done all the
right things, but then it doesnt work.

---
Not to worry; we (me, anyway) all learn by trial and error. :)

--
John Fields


Thanks John, I'm glad it works sorta the way it is suppose to. I think I
have read about 5 or 10 of similar circuits and some of them they call
them
latching. I must have had that confused.

Yes the "hump" is NOT connected. -thanks.

When you say

Make sure you have the capacitor connected to the junction of R3 and
R4 _only_, and that the gate of the TRIAC is _only_ connected to R5
and IC1-4.


I do have the Cap between R3 and R4. From there the cap is connected to
a
common line that has the R5 / MT1 and load connected up to it. (bread
board).


4-------Gate
|
.01u R5 MT1
|______|_____|______(Load)__



Look at the datasheet for the MOC3010. There is a sample circuit which
could be better for powering a lamp.

http://www.fairchildsemi.com/ds/MO/MOC3010-M.pdf

See Figure 6.

--
Regards,
Robert Monsen

"Your Highness, I have no need of this hypothesis."
- Pierre Laplace (1749-1827), to Napoleon,
on why his works on celestial mechanics make no mention of God.
Click to expand...
Thanks for that. I did actually do some other circuits like the one you
indicated. Although I used a 3031 (as I recall) The reading I did seemed to
indicate that the 3031 does the Zero thing which minimized RF if there are
TV's/ Radio etc around. At least that seem to be what I understood. I kinda
wish that people would actually tell us the parts they used and then give us
the theory as to how to arrive at the right part. This would help me anyway.
If I can see exactly what they used. This way I can figure out their math
and test mine and hopefully come to the same conclusions. When I finish a
little project I write the my observations, and what chips I used that
worked so Next time I dont have to expriment all over again.

Regards
 
John,

You are seeing that the circuit does not work as expected or suggested when
the circuit was offered. There was not enough information to hint at the
potential problem of gate sensitivity or special selection of components.
Ray


"John Fields" <jfields@austininstruments.com> wrote in message
news:0uneq059a99pa041no214cts7s82sh8n9e@4ax.com...
On Fri, 26 Nov 2004 11:38:45 -0500, "rayjking"
rayjking@bellsouth.net> wrote:

Stacy,

You are seeing what happens when a circuit is built with trial and error
or
leaving out the most important parameter such as gate current sensitivity
range for the triac. Also there are many thousands of folks that dabble
in
electronics that are successful in building one circuit that works. It is
quite another answer for a circuit that is described in enough detail to
be
mass produced or copied with the expectation of working.
The above issues are the difference between the digital designs and
analog
designs.

---
They are???

In what respect?

--
John Fields
Click to expand...
 
On Fri, 26 Nov 2004 16:18:01 -0500, "rayjking"
<rayjking@bellsouth.net> wrote:

John,

You are seeing that the circuit does not work as expected or suggested when
the circuit was offered. There was not enough information to hint at the
potential problem of gate sensitivity or special selection of components.
Click to expand...
---
Most of us here reply to newsgroup posts by bottom-posting, so if you
don't mind please follow that convention.

You misunderstood my post. What I was questioning was your statement
that:

"The above issues are the difference between the digital designs and
analog designs."

Which makes no sense to me. What were you trying to say?

--
John Fields
 
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