Dear all, I have a 12 volt “mighty Max” gel battery model YTX7L-BSGEL and connecting direct to the “Battery Tender” 12-volt Junior Automatic battery charger continuously charging in the attic. I made a one SCR alarm and connect all these together for the home protection for my 4 years and 6 years old kids at home in case of emergency.

This alarm system however, activated by itself all the time. I believed the battery continually charged and the power surged that make this interruptedly alarm on and off uncontrollably.

 

Welcome to AAC!
That circuit won't work as you want it to. I suggest you read up about how SCRs are triggered and switched off.

 

Welcome to AAC!
That circuit won't work as you want it to. I suggest you read up about how SCRs are triggered and switched off.

Thank you Alec_t,
It does work very well without the "Battery Tender" charger. I can turn on the S1 to activate the alarm. I push the S2 then it stop. I think that I need to add something in between the (battery + charger) to the SCR circuit. Thank you look in to my problem.

 

the triode(thyristor) can jump ON at sharp forward voltage spike https://www.electronicshub.org/scr-turn-on-methods/

 

It does work very well without the "Battery Tender" charger. I can turn on the S1 to activate the alarm.

That doesn't make sense. S1 is in the wrong place. When you apply power, the gate is pulled up to the supply which will turn the SCR on; regardless of whether you have the charger connected or not.

 

unless the thyristor is a triac ... http://class.ece.iastate.edu/ee330/miscHandouts/AN_GOLDEN_RULES.pdf
https://www.nutsvolts.com/magazine/article/triac_principles_and_circuits_part_1
. . . considering Mr. Cappels response
? GTO (i haven't had one) https://www.daenotes.com/electronics/industrial-electronics/gate-turn-OFF-thyristor-GTO , https://www.electronicshub.org/gate-turn-off-thyristor/

 

Regardless of what you want to do with S1 (my guess is that it is there to disable the alarm but in series with the battery gives you the benefit of using S1 to turn it off once triggered), things turning on and off in the house (thermostats, lights, the stove or oven, etc.) can cause electromagnetic pulses that can be picked up by the gate circuit. I suggest that you place a resistor in between the gate and the rest of the circuit (220 ohms or more) and put a 0.1 uf ceramic capacitor from the gate to the anode. If that doesn't solve the problem, increase the resistor and/or capacitor value.

 

Dear Mr. Dickcappels, ci139, and dl324,
Thank for your suggestions. It was working perfect outside of the wall (tested for two months) and before connected to the charger. Please help me look at my picture alarm1. I might drew the S1 or S2 in the wrong place(sorry!). My main problem is that.
After put it to work in the wall (to protect my two little boys when they are at home alone). S1 did activated the alarm, S2 did stop the alarm. However, about 5 or 7 hours later, the unit activated that alarm by itself. I pressed the S2 to stop it them about 4 hours later. it alarms again.
I think, maybe the charger direct to the battery and the circuit might caused surged to this problem. I used SCR # TYN610. To Mr. Dickcappels Thank for suggestion, however, the problem still remain.

 

Here's the pinout for someone who can make out the connections better than me:

to protect my two little boys when they are at home alone

How is an alarm supposed to protect two children who should never be left home alone to begin with?

 

Thank Dennis,
You are right, but when you at work and mom need to go to school. Once in a while we need exception. My problem is that, This unit tested out for two months and S1 activated the alarm. S2 stop the alarm.
After two months of testing, yesterday I put it in the wall also connected the charger. 6 hours later activated by itself...stop S2... then 4 -5 hours activated by itself again.
Do you or anyone can help me with a simple device to connect from the charging battery to the unit? (adding a diode? or transistor unit?

 

the document has a similar circuit with explanations http://resource.download.wjec.co.uk...18_3-3/eng/gce-electronics-book-chapter-8.pdf

and a more similar http://www.payatel.ru/262-shema-odnoknopochnogo-vyklyuchatelya-signalizacii.html
. . . and actually not - coz the load is a relay that switches K1 ON if it's on and OFF if the tyristor is not conducting (load/alarm) being commuted by a relay ←← has 1 button ON OFF control however (but the prev link likely had more reliable schematics . . . and also not but they help to understand what D.Cappels was on about)

about (warning :: it's a simulation = not real ; it does not match your thyristor = it likely does not behave/responce exactly alike)
src. http://tinyurl.com/y59wdm8c
since the long wiring may favour the pickup of EMF the switches must be local near to thyristor . . . such as couple of 12V relays http://tinyurl.com/y2jfd7b2

 

Do you or anyone can help me with a simple device to connect from the charging battery to the unit?

You must have the gate floating when S1 is opened. Put a resistor from gate to ground to prevent the gate from picking up spurious signals.

You didn't give a value for R1. It might need to be a little smaller to account for the small current in R2.

 

Adding the battery charger couples the whole alarm to the AC line via the charger's transformer inter-winding capacitance.
This provides a path for transient currents coupled to the switch circuit, that's why it worked ok without the charger.

When it's floating, (no charger) the whole circuit floats, transients coupled into the wiring have no path for current flow, so the SCR doesn't fire.

Add a 1 uF capacitor between the Gate and Cathode to help shunt the transients.

 

Dear Dl324,
Thank for the suggestion and the schematic. I will try it after work.
Thank

 

Dear Sensacell,
It is " Add a 1 uF capacitor between the Gate and Cathode to help shunt the transients." or add a 1uF capacitor between the Gate and Anode?
Thank you for helping.

 

Consider the point being made by @ci139 in post #4: an induced spike in the anode to cathode voltage can cause an SCR to trigger, in addition to the problems noted elsewhere in this thread.

For this problem a snubber circuit is usually used. For a quick check make a series circuit of about 10 ohms and 0.1 uf and place this combination from the anode to cathode.

There are more things to try if this does not solve the problem.

By the way, what is the part number of the SCR you are using? If it is in this thread I missed it.

There is a related post by this TS at:
https://forum.allaboutcircuits.com/...elp-of-c1-connecting-g-to-a-or-g-to-k.162560/

 

It may be the charger - a regulator from the battery powering your alarm should help.

Battery Tender Plus by Deltran
The Battery Tender Plus, like the others in this comparison, is claimed to be a three–stage charger/maintainer. That being the case, the bulk charge mode should hold a current at or close to the unit’s maximum output until the battery voltage is at or near gassing voltage. That didn’t happen with the first example we tested. When the Tender was first turned on with battery voltage at 12.5, the unit began charging at 1.34 amps.
The current waveform taken at 12.75 battery volts showed the current still slightly above manufacturer specs, though it had dropped noticeably in a very short time. By the time the battery had reached 13.4 volts, the charge rate was down to 0.9 amps. The charge rate continued to drop dramatically, and the rate of voltage rise slowed just as dramatically.
The battery eventually reached 13.88 volts and went no higher. After about six hours in the absorption mode, the unit stopped charging. It then went into float mode at 12.90 volts.
Suspecting a defective unit, we obtained two others and tested them in the same manner. Both of these additional units held maximum current output (1.25 amps) up to 13.75 volts, then began a tapering, constant voltage charge commensurate with the battery’s natural absorption rate and the unit’s temperature compensation scheme. One achieved 14.1 volts before “floating.” The other went to 14.4 volts, but both required significantly longer than the other products to reach that level. That’s not an issue if storage was your reason for attaching the Tender. But if you’ve accidentally left your key on, don’t plan to go anywhere for a while if you want to completely recharge your battery. Deltran states that the battery may be returned to service at around the 80 percent state of charge. But based on the existing loads and charge output of the average Gold Wing, we’d prefer to completely recharge the battery before riding off.
We had been told by one informed source that the Tender was programmed to charge to 14.4 volts, then hold the battery there for around six hours for a thorough charge. That seemed to be the case until we hooked the Tender to a battery that had just been charged with one of the competitors in this test. In that particular case, the absorption mode lasted only ten minutes before the voltage rose to 14.4, and the steady green “charged” light came on. We therefore conclude that like the other units in this test, the absorption mode terminates when the battery’s current acceptance rate falls below a certain level.
When a 4-amp load was placed on the battery, the Tender didn’t respond as the other units had. The green “charged” light remained on. The charger ramped up its output until the load was removed. It then cut back its output and gradually brought the battery back up to float voltage. All of the other brands tested here, after being subjected to a 4-amp load, completed a charge to around 14.4 volts before reverting to float. In the float (maintenance) mode, of the three Battery Tender examples tested, one simply allowed the battery to slowly discharge to around 12.4 volts. A second unit allowed the battery voltage to drift between 12.75 and 12.95 volts. The third unit, newly purchased, held the voltage at 13.15 for two days before allowing it to drift down to 12.89.

source: http://archives.wingworldmag.com/august2002/magazine/article/battery.html

 

Hi Wolframore,
Thank you for let me know about the Battery Tender. My main concern at this moment is that will this Battery Tender constantly charge my gel battery "Mighty Max 6A 12volt) in the attic with constantly charging and would not destroy my battery? (Junior?) 12v and 750mA. I also interested of low draining.
Thank

 

My main concern at this moment is that will this Battery Tender constantly charge my gel battery "Mighty Max 6A 12volt) in the attic with constantly charging and would not destroy my battery? (Junior?) 12v and 750mA.

The specs say it switches to float charging after the battery is charged.


batteryuniversity.com has a wealth of information on batteries:
https://batteryuniversity.com/index.php/learn/article/lead_based_batteries

 

Hi dl324 Mr. Dennis,
Thank you very much for your help. I just completed the SCR as you guided me. For R1 I used 2.7k; R2 is 10k + 0.1uF from the schematic you showed me. I also added a (diode + 0.1uF parallel) from battery to the unit. From Mr. Dickcapples suggested I included (a series circuit of about 22 ohms and 0.1 uf and place this combination from the anode to cathode.) my SCR is TNY 601... I would like to thank all of you! and I will test it this weekend.