I will make a layout for a power supply and later I will make the speaker protection 🙂 I can't wait to make the other channel but need that good thinking mister Mile , I might forget that.
Regards
Juan
Apex NE555 Protection
Hi mister Mile, I read all pages of this thread and I decide to do the AX20 my own pcb design with NE555 protection inside, because I have some experience. I done, but I started test the protection alone first, the problem is when I conect 12VAC, few seconds ago the rele goes on and off and never stop this process until I put some hot in NTC (rele goes on), but when the NTC become cold the on / off process start again. I check and recheck the components and pcb design and I did not found errors. Can you help me ? With your good ideas 🙂
Pozdrav in advance
Hi mister Mile, I read all pages of this thread and I decide to do the AX20 my own pcb design with NE555 protection inside, because I have some experience. I done, but I started test the protection alone first, the problem is when I conect 12VAC, few seconds ago the rele goes on and off and never stop this process until I put some hot in NTC (rele goes on), but when the NTC become cold the on / off process start again. I check and recheck the components and pcb design and I did not found errors. Can you help me ? With your good ideas 🙂
Pozdrav in advance
Just an off the cuff comment in the hope its appropriate...
The NE555 must have a 100uf cap directly across pins 1 and 8 to absorb the huge current spike the device draws when changing state. Without and the device can just keep resetting itself. Also make sure pin 5 ? is correctly decoupled.
The NE555 must have a 100uf cap directly across pins 1 and 8 to absorb the huge current spike the device draws when changing state. Without and the device can just keep resetting itself. Also make sure pin 5 ? is correctly decoupled.
Thanks very much Mooly, I am not a electronic engineer, sorry, so here de questions. Cap 100uf is there, is ok, I Think 🙂 but I changed the value of decouple capacitor 15n to 470n, did I something wrong ? with this value DC protect work, delay work but if I hot NTC nothing happens.
Thanks Mooly
Thanks Mooly
So you have the 100uf cap and pin 5 is decoupled by either a 15 or 470nf. I would have to see the circuit and how this this NTC is wired and what it does 🙂
(if you mean the NTC is a soft start then the problems could be that the NE555 supply is rising to slowly... but that's just a guess... I haven't followed the thread closely enough so would have to see the exact circuit you have used)
(if you mean the NTC is a soft start then the problems could be that the NE555 supply is rising to slowly... but that's just a guess... I haven't followed the thread closely enough so would have to see the exact circuit you have used)
NE555 triger if voltage is from 1/3Vcc nad 2/3Vcc, you must add resistors in series and parallel conection with NTC to keep voltage over 1/3Vcc and under 2/3Vcc whan NTC cold, if NTC hot voltage must drop under 1/3Vcc to triger NE555.
Regards
Hi mister Mile, thanks for your quick reply, but where can I get the Vcc as you say ? Should I get between NTC terminals ?
Regards
Regards
Hi mister Mile, again 🙂 I put a trim instead 100R and the other trim in parallel with NTC. NTC cold I have 5,3Vcc between pins 2,6 to ground and rele ON, NTC hot 5,5Vcc (nothing happens). It should be under 1/3Vcc am I wrong ?
Regards
Regards
NTC must have 10k cold and about 1k hot. If NTC is 1k voltage on pins 2,6 increase over 2/3 Vcc and NE555 disconnect relay.
Attachments
sr200
Hi Mr Apex
I have a question .
Can i use Bf493 instead of 2N5401 TO sr 200 studio ref?
Thanks.
Hi Mr Apex
I have a question .
Can i use Bf493 instead of 2N5401 TO sr 200 studio ref?
Thanks.
Last edited:
P { margin-bottom: 0.21cm; direction: ltr; color: rgb(0, 0, 0); }P.western { font-family: "Times New Roman",serif; font-size: 12pt; }P.cjk { font-family: "WenQuanYi Micro Hei"; font-size: 12pt; }P.ctl { font-family: "Lohit Hindi"; font-size: 12pt; }A:visited { }A:link { } [FONT=Times New Roman, serif]Dear mister Mile, I’m a little bit puzzled about this circuit, since you say I need to use an NTC to sense the temperature.[/FONT]
[FONT=Times New Roman, serif]Starting from de DC protection, Q23 and Q24 will impose approximately 0V when DC appears at Amplifier output.[/FONT]
[FONT=Times New Roman, serif]While in DC fault, trigger will happen when Pin2 (=Pin6) goes lower than 1/3Vcc because Pin2 will SET the output to Vcc, deenergizing relay coil. No doubt about.[/FONT]
[FONT=Times New Roman, serif]Starting condition: C52 will wake up discharged, therefore Pin2 (=Pin6) will SET output to Vcc disabling relay, and will charge through R116 till Pin6 (=Pin2) will reach 2/3Vcc. At this point, Pin6 will RESET the output to 0V energizing relay coil. No doubt once more.[/FONT]
[FONT=Times New Roman, serif]In that case, it seems to me that when we need that 555 output should be SETED to VCC in order to deenergize relay coil, we need that Pin2 (=Pin6) should be forced to go lower than 1/3Vcc, and the only way to accomplish that, concerning thermal protection, is to increase voltage through thermistor while temperature should also increase, therefore a PTC should be needed. Am I right? Or completely confused?[/FONT]
[FONT=Times New Roman, serif]Pozdrav[/FONT]
[FONT=Times New Roman, serif]Starting from de DC protection, Q23 and Q24 will impose approximately 0V when DC appears at Amplifier output.[/FONT]
[FONT=Times New Roman, serif]While in DC fault, trigger will happen when Pin2 (=Pin6) goes lower than 1/3Vcc because Pin2 will SET the output to Vcc, deenergizing relay coil. No doubt about.[/FONT]
[FONT=Times New Roman, serif]Starting condition: C52 will wake up discharged, therefore Pin2 (=Pin6) will SET output to Vcc disabling relay, and will charge through R116 till Pin6 (=Pin2) will reach 2/3Vcc. At this point, Pin6 will RESET the output to 0V energizing relay coil. No doubt once more.[/FONT]
[FONT=Times New Roman, serif]In that case, it seems to me that when we need that 555 output should be SETED to VCC in order to deenergize relay coil, we need that Pin2 (=Pin6) should be forced to go lower than 1/3Vcc, and the only way to accomplish that, concerning thermal protection, is to increase voltage through thermistor while temperature should also increase, therefore a PTC should be needed. Am I right? Or completely confused?[/FONT]
[FONT=Times New Roman, serif]Pozdrav[/FONT]
For thermal protect Vref must be over 2/3Vcc on cold amp and under 1/3Vcc on 90deg. This can be done useing NTC or PTC resistors in circuit.
