I am in need of a solid state relay that latches upon reception of a
positive-going pulse, and holds that state until the power to it is removed.
Actually something that will provide either a logic 1 or a logic 0 for
another device upon reception of said pulse, and hold that state until power
is removed. What would that be called, and where should I look for it? Can
it build it out of OR/AND gates, like a Johnson Counter? Or can it just
buy it like I can buy a CD4017? (I think that's a 0-9 counter...)

Thanks for any help.

Dave

On Mar 13, 4:01 pm, "Dave" <db5...@hotmail.com> wrote:
> I am in need of a solid state relay that latches upon reception of a
> positive-going pulse, and holds that state until the power to it is removed.
> Actually something that will provide either a logic 1 or a logic 0 for
> another device upon reception of said pulse, and hold that state until power
> is removed. What would that be called, and where should I look for it? Can
> it build it out of OR/AND gates, like a Johnson Counter? Or can it just
> buy it like I can buy a CD4017? (I think that's a 0-9 counter...)
>
> Thanks for any help.
>
> Dave


Transistor?

Dave wrote:

> I am in need of a solid state relay that latches upon reception of a
> positive-going pulse, and holds that state until the power to it is removed.
> Actually something that will provide either a logic 1 or a logic 0 for
> another device upon reception of said pulse, and hold that state until power
> is removed. What would that be called, and where should I look for it? Can
> it build it out of OR/AND gates, like a Johnson Counter? Or can it just
> buy it like I can buy a CD4017? (I think that's a 0-9 counter...)
>
> Thanks for any help.
>
> Dave
>
>
RS flip flop.
or,
if you're trying to power up something with a control lock relay..
you can use a double pole relay. 1 pole is used to power the device for
example and the other is used to latch it self on.

But I don't know what you're trying to control?



http://webpages.charter.net/jamie_5"

<mrdarrett@gmail.com> wrote in message
news:b8dbc432-331e-48d9-847e-923437f9aa0e@d21g2000prf.googlegroups.com...
> On Mar 13, 4:01 pm, "Dave" <db5...@hotmail.com> wrote:
>> I am in need of a solid state relay that latches upon reception of a
>> positive-going pulse, and holds that state until the power to it is
>> removed.
>> Actually something that will provide either a logic 1 or a logic 0 for
>> another device upon reception of said pulse, and hold that state until
>> power
>> is removed. What would that be called, and where should I look for it?
>> Can
>> it build it out of OR/AND gates, like a Johnson Counter? Or can it just
>> buy it like I can buy a CD4017? (I think that's a 0-9 counter...)
>>
>> Thanks for any help.
>>
>> Dave
>
>
> Transistor?

Well, a transistor will change if the input to it changes. I'm looking for
something that locks on until the power to it is cut.

Thanks,

Dave

"Jamie" <jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote in message
news:ycjCj.15961$bg.13083@newsfe06.lga...
> Dave wrote:
>
>> I am in need of a solid state relay that latches upon reception of a
>> positive-going pulse, and holds that state until the power to it is
>> removed. Actually something that will provide either a logic 1 or a logic
>> 0 for another device upon reception of said pulse, and hold that state
>> until power is removed. What would that be called, and where should I
>> look for it? Can it build it out of OR/AND gates, like a Johnson
>> Counter? Or can it just buy it like I can buy a CD4017? (I think that's
>> a 0-9 counter...)
>>
>> Thanks for any help.
>>
>> Dave
>>
>>
> RS flip flop.
> or,
> if you're trying to power up something with a control lock relay..
> you can use a double pole relay. 1 pole is used to power the device for
> example and the other is used to latch it self on.
>
> But I don't know what you're trying to control?
>
>
>
> http://webpages.charter.net/jamie_5"
>

Hey Jamie,

An RS flip-flop. Will have to check that out. I am already working with
4027 JK flip-flops, so maybe I am missing the obvious...

What I am trying to control is a 74HC4053, and whether it connects the A and
B outputs to a logic 0 (a0/b0) or a logic 1 (a1/b1). Basically, whether it
connects the J and K of a 4027 JK flip flop to ground or 5V. This would
lock it into it's current state, or allow it to continue responding to the
clock input.

Thanks for the input. Much appreciated.

Dave

"Dave" (db5151@hotmail.com) writes:
> I am in need of a solid state relay that latches upon reception of a
> positive-going pulse, and holds that state until the power to it is removed.
> Actually something that will provide either a logic 1 or a logic 0 for
> another device upon reception of said pulse, and hold that state until power
> is removed. What would that be called, and where should I look for it? Can
> it build it out of OR/AND gates, like a Johnson Counter? Or can it just
> buy it like I can buy a CD4017? (I think that's a 0-9 counter...)
>
> Thanks for any help.
>
> Dave
>
>
An SCR. Apply a control voltage, the "diode" conducts and stays in
conduction until power is removed from the "diode". The control voltage
can disappear as soon as it triggers the SCR, the SCR will continue
to conduct until voltage is removed from the "diode" portion.

If I recall properly, you can synthesize them with a pair of transistors.

Michael

"Michael Black" <et472@FreeNet.Carleton.CA> wrote in message
news:frcvv0$2ob$1@theodyn.ncf.ca...
> "Dave" (db5151@hotmail.com) writes:
>> I am in need of a solid state relay that latches upon reception of a
>> positive-going pulse, and holds that state until the power to it is
>> removed.
>> Actually something that will provide either a logic 1 or a logic 0 for
>> another device upon reception of said pulse, and hold that state until
>> power
>> is removed. What would that be called, and where should I look for it?
>> Can
>> it build it out of OR/AND gates, like a Johnson Counter? Or can it just
>> buy it like I can buy a CD4017? (I think that's a 0-9 counter...)
>>
>> Thanks for any help.
>>
>> Dave
>>
>>
> An SCR. Apply a control voltage, the "diode" conducts and stays in
> conduction until power is removed from the "diode". The control voltage
> can disappear as soon as it triggers the SCR, the SCR will continue
> to conduct until voltage is removed from the "diode" portion.
>
> If I recall properly, you can synthesize them with a pair of transistors.
>
> Michael
>
>

Aaahhh. Yes, I remember this from school. A circuit that stays on even you
try to turn it off... That's what I need. An SCR. Will look into that.
*Thank you, Michael.*

Much appreciated.

Dave

On Mar 14, 3:41=A0pm, "Dave" <db5...@hotmail.com> wrote:
> <mrdarr...@gmail.com> wrote in message
>
> news:b8dbc432-331e-48d9-847e-923437f9aa0e@d21g2000prf.googlegroups.com...
>
>
>
>
>
> > On Mar 13, 4:01 pm, "Dave" <db5...@hotmail.com> wrote:
> >> I am in need of a solid state relay that latches upon reception of a
> >> positive-going pulse, and holds that state until the power to it is
> >> removed.
> >> Actually something that will provide either a logic 1 or a logic 0 for
> >> another device upon reception of said pulse, and hold that state until
> >> power
> >> is removed. =A0What would that be called, and where should I look for i=
t?
> >> Can
> >> it build it out of =A0OR/AND gates, like a Johnson Counter? =A0Or can i=
t just
> >> buy it like I can buy a CD4017? =A0(I think that's a 0-9 counter...)
>
> >> Thanks for any help.
>
> >> Dave
>
> > Transistor?
>
> Well, a transistor will change if the input to it changes. =A0I'm looking =
for
> something that locks on until the power to it is cut.
>
> Thanks,
>

Look at this one shot:
http://www.discovercircuits.com/DJ-Circ ... eshots.htm

If you want it to accept just one trigger pulse only try a JK flip
flop with k=3D0 and your trigger to J. If it powers up in an undermined
state (I'm not sure if this is the case), hold k high temporarily with
a capacitor to power and a resistor to ground, the power on reset time
will be about RC.

At least that's my first guess.

Cheers

On Fri, 14 Mar 2008 08:26:28 -0500, "Dave" <db5151@hotmail.com> wrote:


>
>Aaahhh. Yes, I remember this from school. A circuit that stays on even you
>try to turn it off... That's what I need. An SCR. Will look into that.
>*Thank you, Michael.*
>
>Much appreciated.
>
>Dave
>
The thing about an SCR is it needs an intiateing current even the
2n5060 needs about 20mA .I found it to be higher on the ones I have
anyway.Then it will hold on as little as 5mA.If all thats okay then
fine.

I have a similiar dilema only for a zero crossing detector.I want it
to latch when the detector senses the zero crossing. I'm looking at
something like this.

http://rocky.digikey.com/weblib/ST%20Mi ... 4V1T77.pdf

Cheap and tiny low power consumption.If you look you can probably find
cheaper and lower power versions.

Search for D-type transparent latches.

Or depending on your application and what your willing to spend there
are latching relays a little pricey though.

"Hammy" <spamme@hotmail.com> wrote in message
news:ju5qt39ouvqussmr45b48uhkt2cjbngdic@4ax.com...
> On Fri, 14 Mar 2008 08:26:28 -0500, "Dave" <db5151@hotmail.com> wrote:
>
>
>>
>>Aaahhh. Yes, I remember this from school. A circuit that stays on even
>>you
>>try to turn it off... That's what I need. An SCR. Will look into that.
>>*Thank you, Michael.*
>>
>>Much appreciated.
>>
>>Dave
>>
> The thing about an SCR is it needs an intiateing current even the
> 2n5060 needs about 20mA .I found it to be higher on the ones I have
> anyway.Then it will hold on as little as 5mA.If all thats okay then
> fine.
>
> I have a similiar dilema only for a zero crossing detector.I want it
> to latch when the detector senses the zero crossing. I'm looking at
> something like this.
>
> http://rocky.digikey.com/weblib/ST%20Mi ... 4V1T77.pdf
>
> Cheap and tiny low power consumption.If you look you can probably find
> cheaper and lower power versions.
>
> Search for D-type transparent latches.
>
> Or depending on your application and what your willing to spend there
> are latching relays a little pricey though.

Aaah, yes. Very interesting, but I think what I am going to do is build the
equivalant of an SCR out of transistors, as my electronics textbook
describes. This will allow me (I think) to select the parameters I want and
tailer them to my exact needs. Or at least that's the present idea. Thank
you for this pointer however. I may yet end up using it.

Take it easy...

Dave

Michael Black wrote:

> "Dave" (db5151@hotmail.com) writes:
>> I am in need of a solid state relay that latches upon reception of a
>> positive-going pulse, and holds that state until the power to it is
>>
>>
> An SCR. Apply a control voltage, the "diode" conducts and stays in
> conduction until power is removed from the "diode". The control voltage
> can disappear as soon as it triggers the SCR, the SCR will continue
> to conduct until voltage is removed from the "diode" portion.
>
> If I recall properly, you can synthesize them with a pair of transistors.
>
> Michael

You can achieve that with a double pole relay, wiring the second switch
into the coils path.

Dave wrote:
> "Hammy" <spamme@hotmail.com> wrote in message
> news:ju5qt39ouvqussmr45b48uhkt2cjbngdic@4ax.com...
>
>>On Fri, 14 Mar 2008 08:26:28 -0500, "Dave" <db5151@hotmail.com> wrote:
>>
>>
>>
>>>Aaahhh. Yes, I remember this from school. A circuit that stays on even
>>>you
>>>try to turn it off... That's what I need. An SCR. Will look into that.
>>>*Thank you, Michael.*
>>>
>>>Much appreciated.
>>>
>>>Dave
>>>
>>
>>The thing about an SCR is it needs an intiateing current even the
>>2n5060 needs about 20mA .I found it to be higher on the ones I have
>>anyway.Then it will hold on as little as 5mA.If all thats okay then
>>fine.
>>
>>I have a similiar dilema only for a zero crossing detector.I want it
>>to latch when the detector senses the zero crossing. I'm looking at
>>something like this.
>>
>>http://rocky.digikey.com/weblib/ST%20Micro/Web%20Data/74V1T77.pdf
>>
>>Cheap and tiny low power consumption.If you look you can probably find
>>cheaper and lower power versions.
>>
>>Search for D-type transparent latches.
>>
>>Or depending on your application and what your willing to spend there
>>are latching relays a little pricey though.
>
>
> Aaah, yes. Very interesting, but I think what I am going to do is build the
> equivalant of an SCR out of transistors, as my electronics textbook
> describes. This will allow me (I think) to select the parameters I want and
> tailer them to my exact needs. Or at least that's the present idea. Thank
> you for this pointer however. I may yet end up using it.
>
> Take it easy...
>
> Dave
>
>

Gate current is no problem, at all. You can get sensitive gate
SCRs that will trigger well below 1 mA. For example, the 2N5060
mentioned in Hammy's post triggers at .2 mA (not 20 mA!)

By all means, experiment with making your own from transistors.
You can have fun, and learn that way. But there is no problem
in getting one that will trigger at low current.

Ed