high voltage photo flash capacitor charger

[steven]

:)ive constructed this timed relay circuit i got off the net it works just right anyhow i disconect the positive input wire to the flyback driver circuit in the high voltage photo flash capacitor charger circuit , so all i have to do is switch the main toggle on then push the button and the relay open circuit to the pos input will close thus setting the circuit to charge the hv capacitor for about 10 seconds then the relay opens again and the circuit then turns off. but i got a big problem with this , the relay wont trigger to close the circuit to start the process at all once i put it in so im stuck and cant figure out why the relay wont work when conected to the circuit when it works ok out of the circuit with a test setup

[audioguru]

Hi Steven,
Is the 555 relay driver's output voltage activating? If it isn't working, please post its schematic.
Charge your battery.
Maybe your relay isn't closing because the HV driver circuit 's current is reducing the battery's voltage below the relay's minimum turn-on voltage. Use a 9V relay that will turn-on with about 6.75V, but still be fine with 12V.

[steven]

:)audio guru i run the relay timer off 12 colts and even tried it with separate 12 volts but when i use it to the circuit it wont work but ony when i use it out of the circuit and with a separate circuit ill post the circuit

[steven]

:)here it is, the flyback driver circuit posted in the high voltage sec tion is the one i run it to i just break the positive wire to the driver circuit then run it to the relay open contacts and from there back to the positive of the driver circuit so when i switch the power on the circuit stays off untill i push the relay circuit button, then when the relay closes for trn seconds thus powering the driver circuit so the hv caps get charged but somehow the relay wont switch that circuit on if i used it like a switch

[audioguru]

Hi Steven,
Where is your "start" button connected on the timer circuit?
That simple timer will activate the relay when power is applied to the circuit until it times-out. Dangerous. A 555 timer circuit won't do that.

Your 4001 timer circuit has 4 gates but you are using only one of them. The inputs of the unused gates should be tied to ground, pins 5, 6, 8, 9, 12 and 13.

You say that the relay won't switch on the high voltage driver circuit. Does the relay activate and apply power supply voltage to the HV driver circuit? If it does, then please post the HV driver circuit's schematic.

[steven]

:)the flyback driver circuit i used for the flyback transformer audio guru is in the high voltage stuff section flyback driver circuit , it is under. it was originally the vortex cannon circuit but i left off part of the circuit and ran the end to my disc shaped flyback transformer thr relay has open contact switch so when i push the button the relay closes for a set time i use 12 volts to power the relay . circuit and the positive input to the driver circuit i interupt that and conect it to the relay open contacts so when i push the button of the relay timer it should activate the relay and close the circuit for me so the chargeing process starts but it wont work

[audioguru]

Hi Steven,
Please answer my questions so that I can help you:
1) On your timer circuit, what does the "start" button connect to. The timer circuit that you posted doesn't have a start button.
2) When you push the button, does the relay activate?

[steven]

:)audio guru ive made a blunder and i apologise to you ive uploaded the wrong relay circiut here is the correct one however ive got to find the circuit for it its somewhere in my big collection i cant beleave this goof up of mine i sincearly apologise

[audioguru]

Hi Steven,
While you are lookin' for the schematic, which IC is it using?
I can't read its label.

[steven]

:)audio guru its a 555 timer its gona be a 3while to find the circuit its in my thousands of circuits so it will be hard to find but ill look for it

[steven]

:)audio guru im haveing trouble trying to find that circuit as i was out of printer paper so i used the back of used printer paper and i may of accidently thrown it out so ill have to draw it up from the circuit allready biult, as soon as i get around to it

[steven]

:)here it is

[steven]

:) c2 is a 0.01uf ceramic capacitor and d1 and d2 are both 1n4148 diodes now if i run lust the positive wire input to the relay and from there to the input post of driver circuit it wont switch the relay but out of the circuit it dose and even with a 12 volts supply to the relay it works if i test it but its just that i cant understand why it wont switch a circuir for me with 2 wires at the relay to close the circuit and switch the pos input on for a set time of 10 seconds

[audioguru]

Hi Steven,
Your 555 timer circuit looks OK but I don't see a local supply bypass cap that most electronic circuits need, and as described in the 555's datasheet. Try adding a 0.1uF ceramic cap and a 10uF electrolytic cap near the 555 from its supply pin to its ground.

1) What is the timer's supply voltage when you are pressing the start button?
2) What is the voltage across the relay coil when you are pressing the start button?
3) What is the resistance of the relay coil?

[steven]

:)audio guru i just biult it from a circuit off the net i dont know the supply voltage to the timer when i press the button but the relay i used is 12 volts rated and i even used 12 volts input to the circuit from a 12 volts lead acid cell battery , as for the 0.1uf ceramic and 10uf electro from supply to ground you recamended if ive got it correct, ill try that to but should i put them parralell the ceramic and elctro, to each other or sieries

[audioguru]

Hi Steven,
You must measure the supply voltage to your timer circuit. If the battery voltage is low, it won't be able to supply the 400mA current spike from the 555's switching.

The supply bypass caps are each connected from the 555's supply pin to ground (in parallel). The ceramic cap is for very high frequencies and the electrolytic for lower frequencies and to supply local current that can't travel quickly through the inductance of the long wires from the battery.

What is the resistance of your relay coil? Maybe it is so low that the resulting high current is too much for the tiny series 1N4148 diode.

[steven]

ive got a 10uf electro already in that circuit ,so do i still add the electro and ceramic in parralell from supply to ground still and i forgot to mention i have a 1n4004 diode across the relay inputs for protection is that nessisary when i got the 2 x 1n4148 diodes , and should i replace the diodes for the same as on the relay , ive written down your recamendations and ill apply these as soon as possible as im flat out at the moment, and the 12 volts lead acid cell battery i used has a full charge to

[audioguru]

Hi Steven,
The 10uF electro in your 555 circuit is the timing cap that has nothing to do with the need for supply bypassing with the 2 additional caps.

I don't know where you connected a 1N4004 since relays don't have inputs. Across the contacts?

I can't remember the circuit of your HV driver so I don't know if a protection diode across the relay contacts will do any good, but it certainly won't do any harm.

I don't know if you should replace the 1N4148 diodes because you don't tell me the resistance of your relay coil. Sure, replace them anyway with 1N400x diodes.

You also don't tell me how much voltage the 555 circuit is putting across the relay coil.

[steven]

audio guru i apologise for the lack of information i was in a war with my partner yesterday and some other times and ive been so distracted that i just let my electronics idle for a few days till i know that i was gona get some uninterupted peace , hang in there audio guru ill get to these

[steven]

:)audio guru i was lucky to be able to get these details as follows without inturuption, the relay coil resistance is 40.4 ohms, the supply voltage to the timer with the test battery was 9.83 volts but its the same as the battery voltage and i dident realize it was low in voltage , now the actual battery i first used to power the relay timer is 12.58 volts and thats the same battery in my high voltage photo flash capacitor charger , so what ever battery i use i was still getting the same small problem , oh i have to go pick up a carton of soft drinks for the women. say you dont have any remote controll to turn the chatterbox partner off do you ha ha ha ha its slowing my progress down in electronics

[audioguru]

Hi Steven,
My wifey used to nag me, "Are you making another one?", "Your LEDs are blinding me" and "Get off the internet". But now that she has taken up knitting and going to cooking school, she doesn't bother me very much!

Ah, now we get to know most of the details of your circuit, except the most important one: What is the voltage across the non-functioning relay coil? But now we can calculate it from the relay coil's resistance and the 555's and 1N4148's spec's.

1) Your battery was dead. I suspected it but even a good battery doesn't help.

2) The 40 ohm relay coil is like a dead short to a little 555 and a little 1N4148. The resistance of the coils in the 12V relays that I use measure 1K and 2.2K ohms.

3) The 555 is rated for up to 200mA of output current. With 200mA, its output typically has a 2.5V loss. Your 40 ohm relay will draw 300mA from 12V. Therefore the 555 will probably have a 3V loss or more. A 3V loss at 300mA results in 900mW of dissipation, which is very close to the 555's maximum temperature rating. It might melt.

4) The 1N4148 is rated for up to 100mA continuous current. With the relay's 300mA it will typically have a voltage drop of 1.1V or more, and might also melt.

So the circuit's voltage loss is 3V or more for the 555 and 1.1V or more for the 1N4148. If you subtract those losses from your 12.58V battery, you end up with only 8.48V or less across the relay coil.
A 12V relay is guaranteed to work with 9V or more.
That's why your circuit doesn't work. Ohm's Law, a couple of measurements and the datasheets explain it all.

When you use a relay with such a low coil resistance, you're going to need a power transistor to drive it.

[steven]

audio guru your a genious anyhow i couldent figure out at first why the relay still worked and the open contacts close ok untill i ran one wire to it the postiive to be closed to switch on the driver circuit when the other negative input ran directly to the neg in of driver circuit , the timer never gets hot nor dose the relay and if i use it away from the circuit like use another battery it works fine and if i rig up another circuit and ran the postive to be closed to the relay open contacts and then to another 12 volts battery and from there to something else it works good at switching it on but when i used it to switch the flyback driver circuit in the hv cap charger on for ten seconds the relay then wont work . ive yet got to put in those 2 capacitors you recamended to see if it makes some difference , as soon as the effects of the war between me and my fiauncee wears off and i know im gona get some uninterupted time to get to this

[audioguru]

Hi Steven,
A voltage measurement across your relay coil will tell you what is happening with your circuit, but not what is happening with your lady.

[steven]

audio guru i fed the relay circuit 12.58 volts left in a 12 volts lead acid cell battery and measured the voltage at the relay it was the same

[audioguru]

Steven, the point of this discussion is that the relay's voltage is too low when driven by a 555 and 1N4148 that are straining so hard to cope with such a high current that they reduce the voltage to the relay. Your 12V relay's coil is probably getting less than 8.5V. Measure it to see. Maybe you were measuring the voltage at the relay's contacts by mistake.