I would like to build a dc protection circuit for speaker using upc 1237.
However I don't really understand the datasheet. Is it possible i do not connect anything to pin 4 of the upc 1237 and still get it to work ?
Can the capacitors used be DC type and resistors be of 0.5W type ?
Thankz.
However I don't really understand the datasheet. Is it possible i do not connect anything to pin 4 of the upc 1237 and still get it to work ?
Can the capacitors used be DC type and resistors be of 0.5W type ?
Thankz.
Hi Buzzy,
it's not so hard to interpret the datasheet.
According to the explanation of the function of pin 4 on page 5 of the datasheet (and the table on page 2) you have to apply at least a voltage of (typ.) 0.74V to let pin 6, the output, pull the load (the relay) to ground potential - connecting the speaker to the amplifier.
The power consumption of R4 will only be one-tenth of a Watt at 60Vrms connected to the diode (see figure 2 of datasheet), so a standard 1/4W resistor will do the job.
No need for 0.5W types at all.
The capacitor connected to pin 2 should be an electrolytic with at least 16V, therefore the reverse voltage of max. -0.23V (see table on page 2 of datasheet) won't harm at all.
For the capacitor on pin 4 a 12V electrolytic should be sufficient.
Good luck.
it's not so hard to interpret the datasheet.
According to the explanation of the function of pin 4 on page 5 of the datasheet (and the table on page 2) you have to apply at least a voltage of (typ.) 0.74V to let pin 6, the output, pull the load (the relay) to ground potential - connecting the speaker to the amplifier.
The power consumption of R4 will only be one-tenth of a Watt at 60Vrms connected to the diode (see figure 2 of datasheet), so a standard 1/4W resistor will do the job.
No need for 0.5W types at all.
The capacitor connected to pin 2 should be an electrolytic with at least 16V, therefore the reverse voltage of max. -0.23V (see table on page 2 of datasheet) won't harm at all.
For the capacitor on pin 4 a 12V electrolytic should be sufficient.
Good luck.
The only resistor that may be over 1/4W is the one setting the max current for the relay....
Follow the link below my post... you will see a protection module on there.. you can follow that link to a page that even has a table for selecting the correct resistors...
Follow the link below my post... you will see a protection module on there.. you can follow that link to a page that even has a table for selecting the correct resistors...
I have built the UPC1237 circuit. How do i test if the circuit is working ? The +Vcc is 62.5V would this be a problem ?
If you keep the voltages at pin 7 and 8 at a maximum of 8V I guess you can go as far as you want since there is no direct connection to Vcc. Nevertheless the datasheet states that the maximum Vcc would be +60V. Everything above is at your own risk.
My advise would be to split the 15k resistor, i.e. into 7k5 + 7k5 and attach from the 'center' tap a zener (for instance a 36V zener) to GND to limit the Vcc to the chip.
Care should be also taken when using more than 60V as supply voltage for the relay and therefore to the output at pin 6. Either you use a seperate (and lower) relay voltage or you have to add an additional zener diode and series resistor to limit the voltage to the maximum of 60V when the output is inactive. If the power consumption for the diode is too much you might have to use a series transistor in addition.
My advise would be to split the 15k resistor, i.e. into 7k5 + 7k5 and attach from the 'center' tap a zener (for instance a 36V zener) to GND to limit the Vcc to the chip.
Care should be also taken when using more than 60V as supply voltage for the relay and therefore to the output at pin 6. Either you use a seperate (and lower) relay voltage or you have to add an additional zener diode and series resistor to limit the voltage to the maximum of 60V when the output is inactive. If the power consumption for the diode is too much you might have to use a series transistor in addition.
Buzzy said:
On power on with no source connected to the module, there should be a short delay, then the relay should click... (As there is no source, there is no DC on the input pin.) An easy way to test if it blocks DC is to repeat but this time with an AA batery connected to the input, NO speaker on the output until the very end please...
The DC should be enough to prevent the relay from clicking on this time...
Please wear protective eyewear, I once shorted the bottom of the PCB (didn't cut leads short enough). It blew out a chip from the midle of the IC... with those high voltages I guess this is always a likelyhood.
Without signal going to the upc1237 the relay should be open right ? So should I connect the amp to the upc1237 to feed it some signal and at the same time i apply dc voltage to see if the relay opens ? Will i ruin my amp this way ?
The resetting is done using the latching function of the upc1237.
I have connected the relay as normally closed. The amp is always connected to speaker.
Thankz.
The resetting is done using the latching function of the upc1237.
I have connected the relay as normally closed. The amp is always connected to speaker.
Thankz.
I have connected up a battery and it does not switch the relay off. I dunno if i have fried the chip. I mistakenly connected the 240V ac to pin 4. But upon connecting correctly i can still hear the realy clicking but it does not detect DC anymore.
Can i check that pin1 is the left most pin when the chip is held facing me with the words right side up?
Can i check that pin1 is the left most pin when the chip is held facing me with the words right side up?
Buzzy said:
Hi Buzzy,
Please be very, very careful. After reading this and some of your other posts I am feeling a little concerned for your safety. 😱
Your user name seems appropriate 😀
regards
Thanks for your concern Greg. I was too excited about getting the circuit to work. Thats why i made such a dumb mistake.
An externally hosted image should be here but it was not working when we last tested it.
I have replaced the upc1237. However the relay does not switch off when i connect the battery across the amp and speaker terminal of the relay as shown in the pic above. I dunno y it wouldn't switch off.
I am only connecting this to one amp terminal instead of connecting 2 amp terminals as shown in the schematic of the upc1237 datasheet. Could this be the problem ?
BTW if using the latch function, the speaker would be disconnected from the amp until the power is off right ? Becoz after i connected the battery to test dc for a short while i removed it before i tested if the relay was still connected.
erm what resistor values are you useing... refering to numbering in datasheet? you may have set the threshold higher than the 1V battery is supplying. Tried adding a second battery?
When you say connecting to one terminal, do you mean connecting just one channel...?
If so, that is not a problem, you can add as many or few as you you want.
Also what is the AC and DC voltage you have connected now?
When you say connecting to one terminal, do you mean connecting just one channel...?
If so, that is not a problem, you can add as many or few as you you want.
Also what is the AC and DC voltage you have connected now?
I have tried 2 batteries giving a 3VDC.
When i said connecting to one terminal i meant that using the chip only for 1 channel. AC is 40.5V and DC voltage to the VCC is 61V.
When i said connecting to one terminal i meant that using the chip only for 1 channel. AC is 40.5V and DC voltage to the VCC is 61V.
This is a pic of the schematic i used ......all the values i used are there.
An externally hosted image should be here but it was not working when we last tested it.
Buzzy I sent you mail, just in case I am wrong on my conclusion, this way we prevent being advocated here...
One thing that I see that you can improve is the relay resistor, based on estimation of coild resistance of 1440R I would suggest about 3k3 here, which should supply te relay with 17.5V @ just under 13mA, which should be ample for a 24V relay.
One thing that I see that you can improve is the relay resistor, based on estimation of coild resistance of 1440R I would suggest about 3k3 here, which should supply te relay with 17.5V @ just under 13mA, which should be ample for a 24V relay.
Buzzy said:
I used a PIC microcontroller to control the output relay.
I also used the PIC inputs to monitor the output for DC.
If it detects DC for 500mS it drops the relay and disconnects the speakers.
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