*************************************************************************
* Inverters to power fluorescent lamps from low voltage DC *
* *
* **** Version 1.13 **** *
* *
* Copyright (C) 1997 *
* Samuel M. Goldwasser *
* Corrections or suggestions to: sam@stdavids.picker.com *
* *
* --- All Rights Reserved --- *
* *
* Reproduction of this document in whole or in part is permitted *
* if both of the following conditions are satisfied: *
* *
* 1. This notice is included in its entirety at the beginning. *
* 2. There is no charge except to cover the costs of copying. *
* *
*************************************************************************
Introduction:
------------
This is a collection of non-intelligent (at least for now) inverter circuits
for operating fluorescent or other similar devices from low voltage DC power
sources. These designs - mostly obtained by reverse engineering commercial
camping lanterns, power inverters, and the like - are all very basic circuits
which use simple oscillators, easy to obtain or construct transformers, and
common power semiconductors.
These designs can easily be modified for other purposes such as powering
photoflash or signal strobes and HeNe lasers.
Additional circuits will be added as they become available. Contributions
are welcome.
Super simple inverter:
---------------------
This circuit can be used to power a small strobe or fluorescent lamp. It will
generate over 400 VDC from a 12 VDC, 2.5 A power supply or an auto or marine
battery. While size, weight, and efficiency are nothing to write home about -
in fact, they are quite pitiful - all components are readily available (even
from Radio Shack) and construction is very straightforward. No custom coils
or transformers are required. If wired correctly, it will work.
Output depends on input voltage. Adjust for your application. With the
component values given, it will generate over 400 V from a 12 V supply and
charge a 200 uF capacitor to 300 V in under 5 seconds.
For your less intense applications, a fluorescent lamp can be powered directly
from the secondary (without any other components). This works reasonably well
with a T5-13W or T8-15W bulb but Q1 does get quite hot so use a good heat sink.
C1 1 uF D2 1N4948 R2
+------||------+ T1 1.2KV PRV 1K 1W
| | +-----|>|-----/\/\---+------o +
| R1 4.7K, 1W | red ||( blk |
+-----/\/\-----+------+ ||( |
| yel )||( +_|_ C2
+ o----------------------------------+ ||( --- 300 uF
| red )||( - | 450 V
| +--------------+ ||( |
| Q1 | ||( blk |
6 to 12 | |/ C +--------------------+------o -
VDC, 2A +----| 2N3055 Stancor P-6134
D1 _|_ |\ E 117 V Primary (blk-blk)
1N4007 /_\ | 6.3 VCT Secondary (red-yel-red)
| |
- o------------+------+
Notes on super simple inverter:
------------------------------
1. Construction can take any convenient form - perf board, minibox, etc.
Make sure the output connections are well insulated.
2. C1 must be nonpolarized type - not an electrolytic.
3. D1 provides a return path for the base drive and prevents significant
reverse voltage on the B-E junction. Any 1 A or greater silicon diode
should be fine.
4. C2 is shown as typical energy storage capacitor for strobe applications.
5. D2 should be a high speed (fast recovery) rectifier. However, for testing,
a 1N4007 should work well enough. R2 limits surge current through D2.
6. The polarity of the input with respect to the output leads is important.
Select for maximum voltage by interchanging the black output wires.
7. Mount Q1 (2N3055) on a heat sink if continuous operation is desired. It
will get warm. Any general purpose NPN power transistor should work. For
PNP types, reverse the the polarities of the power supply and D1, and
interchange one set of leads (where a diode is used for DC output).
8. Some experimentation with component values may improve performance for
your application.
9. When testing, use a variable power supply so you get a feel for how much
output voltage is produced for each input voltage. Component values are
not critical but behavior under varying input/output voltage and load
conditions will be affected by R1 and C1 (and the gain of your particular
transistor).
10. WARNING: Output is high voltage and dangerous even without large energy
storage capacitor. With one, it can be lethal. Take appropriate
precautions.
11.
| | |
---+--- are connected; ---|--- and ------- are NOT connected.
| | |
Low power fluorescent lamp inverter 1:
-------------------------------------
The circuit below was reverse engineered from a model number FL-12 'Made
in Hong Kong' battery (8 AA cells) or 12 V wall adapter powered portable
fluorescent lamp. The bulb is an F8-T5.
This design can easily be modified for many other uses at lower or higher
power. Note that its topology is similar to that of the circuit described
in the section: "Super simple inverter".
C2 .01 uF
+------||------+ T1 3
| | +------------+-+
| R1 1.5K | 4 o ||( | |
+-----/\/\-----+------+ ||( +---+
| 15T F )||( | |
| 1 )||( | | FL1
+ o-----+----------|---------------------+ ||( O 350 T | | F8-T5
| | )||( | |
| | 20T D )||( | |
| R2 / 2 )||( | |
| 68 \ +-------+------+ ||( +---+
6 to 12 _|_ C1 / Q1 | | ||( | |
VDC --- 100 uF | | | +---+--------+-+
| 16 V | |/ C | |
| +----| 5609 +---------------+
| C3 _|_ |\ E NPN O = Output
| .027 uF --- | D = Drive
| | | F = Feedback
- o-------+----------+------+
Notes on low power fluorescent lamp inverter 1:
----------------------------------------------
1. T1 is an E-core ferrite transformer. The core is 5/8" x 3/4" x 3/16"
overall. The outer legs of the core are 3/32" thick. The central leg is
3/16" square. The square nylon bobbin has a diameter of 5/16". There is
no visible spacer between the cores but I did not disassemble to confirm.
The 350T O (Output) is wound first followed by the 25T D (Drive) and 18T F
(Feedback) windings. There should be a strip of mylar insulating tape
between each of the windings.
The number of turns were estimated without disassembly as follows:
* The resistances of each of the windings was measured to determine the
arrangement of the transformer.
* The inverter was run at just enough input voltage for it to oscillate
(so the load of the fluorescent tube would not affect the readings) and
the voltages on all 3 windings were measured on an oscilloscope.
From this, the ratios for the windings were determined.
* An estimate was made of the number of turns likely to be on the Drive
winding based on other similar designs. The number of turns on the
other windings were calculated based on the turns ratios. Wire size
is probably #36 AWG.
2. The transistor was marked 5609 which I could not cross to anything. I
would guess that a general purpose medium power transistor like a 2N3053
or ECG24 would be suitable. For PNP types, reverse the polarities of the
power supply and C1.
Since it is very low power, no heat sink is used in this lamp. However,
for other applications, one may be needed.
3. Some experimentation with component values may improve performance for
your application.
4. When testing, use a variable power supply so you get a feel for how much
output voltage is produced for each input voltage. Component values are
not critical but behavior under varying input/output voltage and load
conditions will be affected by C2, C3, R1, R2, the number of turns on each
of the windings of T1, and the gain of your particular transistor.
5. WARNING: Output is high voltage and dangerous. Take appropriate
precautions.
6.
| | |
---+--- are connected; ---|--- and ------- are NOT connected.
| | |
Low power fluorescent lamp inverter 2:
--------------------------------------
The circuit below is the type used in inexpensive fluorescent camping lanterns.
It will drive T5-4W to T5-13W tubes depending on input voltage. The power
source can be a 4 to 9 V 2 A power supply (depending on the size of your lamp)
or a suitable battery pack. This design was reverse engineered from a random
commercial unit of unknown manufacture.
o T1
+ o----+---------+-------------------+
| | )|:| o C2
| S1 | D 20T )|:| +-------||-----+-+
| Start |- #26 )|:|( .022 uF | |
| | )|:|( 600 V +---+
| | +-------+ |:|( | |
| R2 \ | |:|( O 250T | |
| 270 / | o |:|( #32 | | FL1
| \ +------|-------+ |:|( | | T5 lamp
+_|_ C1 | | | F/S 7T )|:|( | |
--- 100 uF | | | #32 )|:| +-------+ | |
- | 16 V +----|------|---+---+ | +---+
| | | | | | |
| | | +-----------------|------+-+
| | +-----------+ |
| S2 | | | | O = Output
| _|_ Off | |/ C | | D = Drive
+-- --+--------+----| Q1 | | F/S = Feedback/starting
| | | |\ E 2SC1826 _|_ D2 |
| \ _|_ | /_\ 1N4007 |
| R1 / D1 /_\ | | |
| 220 \ 1N4148 | | | |
| | | | | |
o-----+-----+--------+------+-----------+---------+
The approximate measured operating parameters are:
Lamp type V(in) I(in) starting/running
-------------------------------------------------------------
T5-4W 3 V .9/.6 A
4 V 1.1/.7 A
5 V 1.3/.8 A
T5-6W 4 V 1.1/.8 A
5 V 1.2/.9 A
6 V 1.4/1.0 A
T5-13W 6 V 1.6/.95 A
7 V 1.7/1.0 A
8 V 1.8/1.2 A
9 V 2.1/1.3 A
No, this circuit does not have over 100% efficiency (the power input is less
than the tube wattage ratings). Obviously, the tubes are not being run at
their full rated power (I have not measured output V and I).
Notes on low power fluorescent lamp inverter 2:
-----------------------------------------------
1. Construction can take any convenient form - perf board, minibox, etc.
Make sure the output connections are well insulated.
2. T1 is assembled on a square nylon bobbin, 3/8" cubed. Wind the 250T O
(Output) first, insulate with mylar tape, 20T D (Drive) next, and 7T F/S
(Feedback/Starting) last. Observe directions of windings as indicated by
the dots (o). The number of turns for the O winding was estimated based
on measured winding resistance, wire size, and the dimensions of the bobbin.
The core is just a straight piece of ferrite 1/4" x 1/4" x 1-3/8" It is
fully open - there is no gap.
3. Any general purpose reasonably high gain NPN power transistor should work.
For PNP types, reverse the polarities of the power supply, C1, D1, and D2.
Use a good heat sink for continuous operation at higher power levels (6 V
input or above). The type used (2SC1826) was a replacement after I fried
the unidentified transistor originally installed.
4. Pushbutton switches are used to control operation. S1 (Start) provides
initial base drive to the transistor via the Feedback/Starting winding of
T1 until the tube arc is established. At that point, feedback is sustained
via current flowing through the tube. S2 (Off) shorts the base of the
transistor to ground to stop the oscillator.
Like a regular manual start preheat fluorescent fixture, the start switch,
must be depressed until the lamp comes on at full brightness indicating that
the filaments are adequately heated.
5. Some experimentation with component values may improve performance for
your application.
6. When testing, use a variable power supply so you get a feel for how much
output voltage is produced for each input voltage. Component values are
not critical but behavior under varying input/output voltage and load
conditions will be affected by R1 and R2 (during starting in particular),
the number of turns on each of the windings of T1, and the gain of your
particular transistor.
7. WARNING: Output is high voltage and dangerous. Take appropriate
precautions.
8.
| | |
---+--- are connected; ---|--- and ------- are NOT connected.
| | |
Archer mini flashlight fluorescent lamp inverter:
------------------------------------------------
The circuit below was reverse engineered from the Archer model number 61-3724
mini fluorescnet/incandescent flashlight combo (no longer in the Radio Shack
catalog). The entire inverter fits in a space of 1-1/8" x 1" x 3/4". It is
powered by 3 C size Alkaline cells and drives a T5-4W tube.
This design can easily be modified for a many other uses at lower or higher
power.
o T1
+ o----+----------+----------------+ o
| | )|:| +--------------+-+
| \ D 28T )|:|( | |
| R1 / #26 )|:|( +---+
| 560 \ +---------+ |:|( | |
| / | |:|( O 315T | | FL1
| | | o |:|( #32 | | T5-4W
| +------|---------+ |:|( | |
| | | )|:|( +---+
+_|_ C1 | | F 28T )|:|( | |
--- 47 uF | | #32 )|:| +--------------+-+
- | 16 V | | +---+
| | | Q1 | O = Output
| | C \| | D = Drive
| C2 _|_ |---+ F = Feedback/Starting
| .022 uF --- E /| |
| | | _|_ C3
| | | --- .022 uF
| | | |
o-----+----------+------+-----+
Notes on Archer mini flashlight fluorescent lamp inverter:
---------------------------------------------------------
1. T1 is an E-core ferrite transformer. The core is 5/8" x 3/4" x 3/16"
overall. The outer legs of the core are 1/8" thick. The central leg
is 3/16" square. The square nylon bobbin has a diameter of 5/16". There
is a .020" gap (spacer) in between the two halves of the E-core.
The 315T O (Output) is wound first followed by the 28T D (Drive) and 28T F
(Feedback) windings. There should be a strip of mylar insulating tape
between each of the windings.
The number of turns were estimated without disassembly as follows:
* The wire sizes were determined by matching the diameters of the visible
ends of the wire for each winding to magnet wire of known AWG.
* The number of turns in the Output winding was determined based on its
measured resistance, core diameter, and the wire gauge tables.
* A 50 KHz .1 V p-p signal was then injected into the Feedback winding.
The amplitudes of the resulting outputs from the Drive and Output
windings were then measured. From these, the ratios of the number of
turns were calculated.
2. The transistor was totally unmarked. Any general purpose reasonably
high gain NPN power transistor should work. For PNP types, reverse the
polarities of the power supply and C1.
Since it is very low power, no heat sink is used in the Archer flashlight.
However, for other applications, one may be needed.
3. Some experimentation with component values may improve performance for
your application.
4. When testing, use a variable power supply so you get a feel for how much
output voltage is produced for each input voltage. Component values are
not critical but behavior under varying input/output voltage and load
conditions will be affected by C2 and C3, the number of turns on each of
the windings of T1, and the gain of your particular transistor.
5. WARNING: Output is high voltage and dangerous. Take appropriate
precautions.
6.
| | |
---+--- are connected; ---|--- and ------- are NOT connected.
| | |
Energizer mini flashlight fluorescent lamp inverter:
---------------------------------------------------
The circuit below was reverse engineered from the Energizer model number
unknown (worn off) mini fluorescent/incandescent flashlight combo. The entire
inverter fits in a space of 1-1/8" x 1-1/8" x 3/4". It is powered by 4 AA
size Alkaline cells and drives a F4-T5 tube.
This design is very similar to the Archer model (see the section: "Archer mini
flashlight fluorescent lamp inverter", but eases starting requirements by
actually heating one of the filaments of the T5 lamp. Thus, a lower voltage
transformer can be used.
o T1 o
+ o----+----------+--------+-------------------+ |:| +----------------+
| | C4 _|_ )|:|( H 16T #32 |
| \ 1000 --- D 32T )|:| +--------------+ |
| R1 / pF | #26 )|:|( | |
| 360 \ +-------------------+ |:|( +---+
| / | |:|( | |
| | | o |:|( O 160T | | FL1
| +--------|-------------------+ |:|( #32 | | F4-T5
| | | )|:|( | |
+_|_ C1 | | F 16T )|:|( +---+
--- 47 uF | | #26 )|:|( | |
- | 16 V | | Q1 +---+ |:| +--------------+-+
| | | MPX9610 |
| | C \| R2 | O = Output
| C2 _|_ |---+---/\/\--- D = Drive
| .047 uF --- E /| | 22 F = Feedback
| | | _|_ C3 H - Heater (filament)
| | | --- .01 uF
| | | |
o-----+----------+--------+-----+
Notes on Energizer mini flashlight fluorescent lamp inverter:
------------------------------------------------------------
1. T1 is an E-core ferrite transformer. The core is 1/2" x 5/8" x 3/16"
overall. The outer legs of the core are 3/32" thick. The central leg
is 3/16" square. The square nylon bobbin has a diameter of 5/16". There
is a .010" (estimate) gap (spacer) in between the two halves of the E-core.
The 160T O (Output) is wound first followed by the 16T H (Heater), 32T D
(Drive), and 16 T F (Feedback) windings. There should be a strip of mylar
insulating tape between each of the windings.
The number of turns were estimated after unsoldering the transformer from
the circuit board as follows:
* The wire sizes were determined by matching the diameters of the visible
ends of the wire for each winding to magnet wire of known AWG.
* The number of turns in the Output winding was determined based on its
measured resistance, core diameter, and the wire gauge tables.
* A 100 KHz .1 V p-p signal was then injected into the Drive winding. The
amplitudes and phases relationship of the resulting outputs from the
Feedback, Heater, and Output windings were then measured. From these,
the ratios of the number of turns and winding start/end were determined.
2. The transistor was an MPX9610. I was not able to locate specs for this
part number but a transistor like a 2N3053 or ECG24 should work. For PNP
types, reverse the polarities of the power supply and C1.
Since it is very low power, no heat sink is used in the Energizer
flashlight. However, for other applications, one may be needed.
3. Some experimentation with component values may improve performance for
your application.
4. When testing, use a variable power supply so you get a feel for how much
output voltage is produced for each input voltage. Component values are
not critical but behavior under varying input/output voltage and load
conditions will be affected by C2 and C3, the number of turns on each of
the windings of T1, and the gain of your particular transistor.
5. WARNING: Output is high voltage and dangerous. Take appropriate
precautions.
6.
| | |
---+--- are connected; ---|--- and ------- are NOT connected.
| | |
Medium power fluorescent lamp inverter:
--------------------------------------
This circuit is capable of driving a variety of fluorescent lamps from a 3 to
12 V, 2 to 3 A DC power supply, or auto or marine battery. With appropriate
modifications (if needed) it may be used for other applications like powering
an electronic flash or HeNe laser tube. The transformer will need to be custom
wound (by you) but this is not really difficult - just slightly time consuming
for the 600 turn O (Output) winding if you don't have a coil winding machine.
I have used it on fluorescent tubes of many sizes: F6-T5, F13-T5, F15-T12,
and F20-T12. The arc will be sustained with the filaments hot on an input
as low as about 3.5 to 4 V (with a new tube) but during starting, an input
voltage of about 5 or 6 V may be needed until the filaments are hot enough
to sustain the arc at the lower voltage.
+Vcc
o Q1 +----------------+
| | )|:|
+ B |/ C )|:|
L1 |:|( +------| 2N3055T )|:| C1
24T |:|( | |\ E D 15T )|:| +----------||---------+-+
#22 |:|( | | #26 )|:|( .0039 uF | |
+ | -_- )|:|( 600 V +---+
| | )|:|( | |
+--|-------------------------+ |:|( | |
| | Q2 _-_ )|:|( | | FL1
| | | )|:|( O 600T | | F5 lamp
| | B |/ E D 15T )|:|( #32 | |
| | ----| 2N3055T #26 )|:|( | |
| | | |\ C )|:|( | |
| | | | )|:|( | |
| | | +----------------+ |:|( +---+
| | | |:|( | |
| | -----------------------+ |:| +---------------------+-+
| | F 10T )|:|
| | #32 )|:|
| | +---------+ |:|
| | | F 10T )|:| T1
| | | #32 )|:|
| +-------------------------+
| |
| R1 | R2
+----------/\/\/\--+--/\/\/\--+
220 22 _|_
1 W 2 W -
The switching frequency is about 21 KHz and varies less than 5 percent over
the range of a lighted bulb (it is significantly different with no load).
The approximate measured input voltage and current are:
V(in) I(in) F13-T5 I(in) F20-T12
----------------------------------------------------
3 V - 1.37 A
4 V 1.76 A 1.52 A (SV)
5 V 1.80 A (SV) 1.60 A
6 V 1.90 A 1.65 A
7 V 1.96 A (FB) 1.70 A
8 V 2.02 A 1.80 A
9 V 2.16 A 1.90 A
10 V 2.33 A 2.05 A (FB)
11 V - 2.30 A
12 V - 2.60 A
Note: SV = Starting Voltage (current is lower), FB = Full Brightness.
Notes on medium power fluorescent lamp inverter:
-----------------------------------------------
1. T1 is an E-core ferrite transformer. Once complete, the cores are installed
on the bobbin with a 2 mm gap. Some experimentation with the core gap may
be needed to optimize performance for a given lamp type and input voltage.
Each E core is 1" x 1/2" x 1/4" overall. The outer legs of the core are
1/8" thick. The central leg is 1/4" square. The square nylon bobbin has
a diameter of 5/16" and length of 3/8".
The 600T O (Output) is wound first followed by the 15T D (Drive) and 10T F
(Feedback) windings. For convenience, wind the D and F windings bifiler
style (the two wires together). Determine the appropriate connections
with an ohmmeter (or label the ends). The centertaps are brought out to
terminals. Try to distribute the O winding uniformly across the entire
bobbin area by winding it in multiple layers. This will assure that no
wires with a significant voltage difference are adjacent. There should be
a strip of insulating tape between the O and the other windings.
2. L1 isolates the power supply. It is 24 turns of #22 wire wound on a 1/4"
ferrite core. The inverter works fine without L1 but seems to have a tad
more strength at low voltage with it.
3. The transistors are 2N3055T (TO220 package) types but are not critical.
However, I expect that some faster switching transistors would run cooler.
Any high gain fast switching NPN power transistor should work. For PNP
types, reverse the polarity of the power supply.
For operation above about 6 V, a pair of good heat sinks will be required.
4. Some experimentation with component values may improve performance for
your application.
5. When testing, use a variable power supply so you get a feel for how much
output voltage is produced for each input voltage. Component values are
not critical but behavior under varying input/output voltage and load
conditions will be affected by C1, the number of turns on each of the
windings of T1, the gap of the core of T1, and the gain of your particular
transistor.
6. WARNING: Output is high voltage and dangerous. Take appropriate
precautions.
7.
| | |
---+--- are connected; ---|--- and ------- are NOT connected.
| | |
Basic 200 W power inverter:
--------------------------
This circuit was reverse engineered from a Tripp-Lite "Power-Verter" Model
PV200 DC to AC Inverter - typical of those used for camping or boating
applications where the only source of power is an auto or marine battery.
This particular model is rated 200 W continuous. There is no regulation or
precise frequency control.
Modifications for higher or lower output voltage are easily achieved. For
example, a fast cycle strobe requiring 330 VDC, would only require using three
times the number of turns on the Output winding and the addition of a bridge
rectifier to charge the energy storage capacitor(s). Alternatively, the
inverter could be used as-is with the addition of a voltage tripler. A tripler
rather than doubler is needed because of the squarewave output. (The RMS and
peak voltages are the same so you don't get the boost of 1.414 as you do with
the sinusoidal waveform from the power company.)
3 o
+12 VDC +--------+--------------+ ||
o | | )||
| |/ C _|_ C1 )||
S F1 20 A +------| Q1 --- 10 uF 31T D )|| 2
| | |\ E -_|_ 160 V #13 )|| +---------o AC Hot
\ S1 | | - )||(
| Pwr | -_- )||(
| | 4 )||(
+------+---|--------------------------------+ ||(
| | | _-_ )||(
| | | | )||( O 360T
| | | |/ E _-_ C2 31T D )||( #20
| / | ----| Q2 -_|_ 10 uF #13 )||(
C3 +_|_ R3 \ | | |\ C --- 160 V )||(
10 uF --- 150 / | | | + | 5 )||(
50 V - | 5 W \ | | +--------+--------------+ ||(
| | | | ||( 1
| | | +---------------------+ || +------o AC Neutral
| | | | 6 o ||
+------+---|-------------------+ +-------+ || T1
| | F 17T )||
| R3 2.7 10 W | #24 7 )|| O = Output
| +----/\/\----+------------+ || D = Drive
| |R2 2.7 10 W 10 o || F = Feedback
| +----/\/\-----------------+ ||
| _|_ F 17T )|| (Pin numbers from
| - #24 8 )|| Triplite unit.)
+--------------------------------+
Notes on basic power inverter:
-----------------------------
1. Construction was all done point-to-point - there is no circuit board.
Layout appears not to be critical.
2. T1 is a relatively large heavy laminated E-I core transformer. The E and I
sheets alternate direction to assure a low reluctance magnetic circuit.
The core dimensions are 3-3/4" x 3-1/8" x 1-1/8" overall. The outer legs
of the core are 5/8" thick. The central leg is 1" wide. The square bobbin
has a diameter of 1-3/8".
The 360T O (Output) secondary is wound first as 4 or 5 insulated layers
followed by the 31T D (Drive) and 17T F (Feedback) windings. There are
insulating layers between each of the windings.
The number of turns were estimated without disassembly as follows:
* The wire sizes were determined by matching the diameters of the visible
ends of the wire for each winding to magnet wire of known AWG and/or
measuring with a micrometer where possible. (The Drive windings are
actually wound using square cross-section magnet wire for maximum packing
density. This was estimated to be equivalent to #13 AWG round wire.)
* The number of turns in the Output winding was determined based on its
measured resistance, core diameter, and the wire gauge tables.
* The inverter was run and the amplitudes of the signals on each winding
were measured. From these ratios, the number of turns were calculated.
3. The transistor were marked 69-206. ECG29 is a close match - high power
amplifier switch - 80 V, 50 A, 300 W, Hfe 20 min. 2SD797 is another
readily available power transistor that should work. For PNP types,
reverse the polarities of the power supply, C1, C2, and C3.
The transistors are mounted on heat sinks which form the sides of the case.
3. C3 and R3 are required for starting. Since there is no source of current
for the bases of the transistors other than the Feedback windings, this
provides a starting pulse to Q2 when the unit is switched on. Ramping the
input voltage slowly rather than using the power switch would likely
result in the inverter behaving like an inanimate object.
4. Measured frequency of operation was about 56 Hz. This is likely affected
by nearly everything - input voltage, capacitance, core saturation, phase
of the moon, etc. Therefore, don't expect to drive a clock mechanism from
this thing with any accuracy!
5. Some experimentation with component values may improve performance for
your application.
6. When testing, use a variable power supply so you get a feel for how much
output voltage is produced for each input voltage. Component values are
not critical but behavior under varying input/output voltage and load
conditions will be affected by C2 and C3, the number of turns on each of
the windings of T1, and the gain of your particular transistors. However,
See note (3) about starting.
7. WARNING: Output is high voltage and dangerous - even more so if you increase
its output for true HV applications. Over 200 W is available continuously.
Take appropriate precautions.
8.
| | |
---+--- are connected; ---|--- and ------- are NOT connected.
| | |
-- end V1.13 --