Op Amp VCC+ to 30V using 5V source?

No. If you get an isolated 5V -> +/-15V converter, you can connect the negative output of the converter to your +5V supply - then the inverter's positive output will be at +35V (and ignore the converter's "output ground" terminal)(but you _must_ use an isolated output converter for this!)

You miss understood him.

the DC-DC converter he is referring to will operate from the 5+ volt supply you have. The converter has 3 wire output for +15 and -15 with the center tap as the common. If you connect the -15 side to your common of the circuit, the +15 output will become +30 output and you don't connect the center tap (common) of the DC-DC's output to anything. look there.

If the impedance of the 30V supply is low, that means one candraw a goodly current from it with low drop. So, from your description of what you saw, the impedance of the 30V supply is too *high*. That DC-DC converter needs some re-engineering.

First disconnect your DC/DC and put a bench supply there at 30V. See the rest of your circuitry works before you mess with the DC/DC.

Depends on your target volume...

Yes, if making less than 10K. If you are making 100K and every penny counts, then a discrete solution might be cheaper.

Delivering 3 to 5mA at 30V is possible, if you fix the circuit. First of all, you want to have maximum current through the inductor during on cycle and hold one end tight during off cycle. The TTL output drivers are not going to hold it tight at positive voltage. In fact, it might even go negative. So, you want one end of the inductor ties to VCC and drive the other end.

Secondly, skip the 1K resistor, which is absorbing all the output load.

Thirdly, increase the inductor by 10 to 20 times. Few hundred uH inductors are available in 1206 SMD, so size is not a problem.

Finally, yes, 12V would be easier than 5V.

So, is there is an inverter / oscillator that I can use that will allow for a 12V input... the one that I am using now can have a maximum of 7V. Also, do you think that I will be able to get a high enough current if I did that?

You are going to have to ditch that circuit. You want a cheap, reliable, easy to build solution? You said you have 12 volts available. Triple it. You can get 30 mA easily from a charge pump. Googling "voltage tripler charge pump" brings up this link:

--- Oh, bullshit...

View in Courier:

The DC to DC converter is a V-INFINITY (CUK) P/N VASD1-S5-D15-SIP, available from Digi-Key as their P/N 102-1341-ND for USD 4.96 qty 1.

The LT1677 is available from Digi-Key as their P/N LT1677CS8-ND for USD 4.50 qty 1.

The 10.2k ohm +/- 1% resistor is available from Digi-Key as their P/N 10.2KXBK-ND for about a dime each, qty 5.

The 1.13k ohm +/- 1% resistor is available from Digi-Key as their P/N 1.13KXBK-ND for about a dime each, qty 5.

So you're good to go for about ten bucks in parts. What was so hard about that?

-- JF

We use BC847s for oscillations and they work up to 60V, which would help absorbs the + and - voltage spikes. As suggested by Mr. Larkin, we also have emitter coil for the oscillator. However, it's going to take a custom made coupled inductor (or transformer). It may or may not be worthy for you. Our budget is $1 for 100K. What is your budget and volume?

Hopefully looking at spending less than $10 or so on the whole circuit, though cost isnt that huge an issue... the "cost" issue is when I purchase parts to build a circuit and it doesnt work like I would want / expect it to :)

Also, quantity is less than 10 units... if I can get a circuit that will power 4 op-amp chips, then this would be golden.

For 10 pieces, it's not sensible to design circuits. Buy a dc/dc converter. JF drew the schematic and found the parts.

John