# Simple 555 dc pulse generator.

Discussion in 'Electronic Design' started by [email protected], Sep 13, 2005.

1. ### Guest

I found a circuit in my electronics book for makeing a dc pulse
generator based on an NE555. The circuit includes a pot for adjusting
the frequency. I am going to use this simple generator for driving an
ignition coil which power a Tesla coil. im wondering if I could build
this circuit and then after the generator, before the coil, place a
voltage divider where on of the resistors is a pot for adjusting the
voltage, and then another pot in series with this output the make a
square wave generator with adjustable voltage, frequency, and current.

2. ### amdxjunkGuest

place a voltage divider where one of the resistors is a pot for adjusting
the
Yes a pot. setup as a voltage divider will allow you to adjust the
output voltage, however I think you will find you need more drive for your
ignition coil. That means your 555 will end up driving the base of a power
transistor or a FET.
If you keep looking you will find a 555 circuit with independently
adjustable on and off times, it has two diodes in the trigger/ discharge
circuit. This will allow you to experiment for the best on time.

Mike K.

3. ### Guest

Thanks. I hadn't realy considered the power levels a 555 can handle, I
had only thought about them breifly. I have a couple of 2N3055's
already mouned on heatsinks I can use. Do you know how many watts a
typical igniton coil can switch? I am hoping for an output of 5-10 kv
at at least 1 ma.

4. ### Winfield HillGuest

wrote...
10 to 20 watts? Considering the inefficiencies, that should
be good for 10 to 20kV, which won't make much of a spark!

5. ### amdxjunkGuest

Hi NG,
I'm not not one to second guess Win,
(except on politics ;-) However I found
this site that suggests the coil will draw
about 5 amps at 6 to 8 volts. The low voltage is
described in the article. About 100 watts at 12 Volts.

Mike K.

6. ### Winfield HillGuest

amdxjunk wrote...
My reference was to the available output power, under actual
operating conditions (not DC). Also, it was a total WAG. :>)
I don't believe it's a good starting point for a Tesla coil.

7. ### amdxjunkGuest

Win, I agree it's probably not the best starting point, however he is a 14
yr old newbie that is smart enough to get some
experience on a 12 v pulsed system before he hooks onto a 12kv 30ma.
continuous
current system.
Mike K.

8. ### Guest

Thank you, newbies about the nicest thing I've heard in this group