Switching - odd power cycling problem

[mth5044]

I'm trying to get a switching layout to work using a PICAXE ucontroller. The code checks out in the programmer, but I'm having a strange time with the power supply.

Schematic:



Circuit explanation: one 7805 feeds the momentary switches (VA -> SW1 and SW2 boards) which, when depressed, send a 5V signal to one of the 8 pins of the PICAXE depending on what button was pushed. The other 7805 supplies power to the PICAXE. Thought I'd keep them separate in case the button connection causes popping or something. The 1-8 inputs on pins 3-10 of the PICAXE are where one half of the buttons connect (the other half being VA). The PICAXE then sends out a 5V through pins 11-19 to 2N3904's which when high, should connect an LED to GND. The LED's all have 9V feeding them constantly (L1+ and L2+) and would light up when the connection is made.

I'm powering the whole thing with a onespot that reads 9.54V. When plugged into the circuit, all 9v connections show a voltage circulating from 1.22V to 0V and pack again at about 1 second periods. I'm getting about 0.5V out of the 7805's output. The LED's are all dimly flashing with the voltage swings. Any ideas as to what could be happening?

Thanks

[artifus]

not familiar with picaxe - which one? does it have a reset pin? should this reset pin have a resistor from + and a capacitor to gnd?

[R.G.]

I'm powering the whole thing with a onespot that reads 9.54V. When plugged into the circuit, all 9v connections show a voltage circulating from 1.22V to 0V and pack again at about 1 second periods. I'm getting about 0.5V out of the 7805's output. The LED's are all dimly flashing with the voltage swings. Any ideas as to what could be happening?

The protection on the 1Spot turns it off for a second or so then tries to restart. My best guess is that you have some kind of miswiring/connection that is taking more than the 1.7A that the 1Spot will provide before protecting, then retrying. I think you're tripping the overcurrent protection.

[mth5044]

not familiar with picaxe - which one? does it have a reset pin? should this reset pin have a resistor from + and a capacitor to gnd?

It's a 20X2 PICAXE, datasheet and circuit setup on pages 30 and 31 of this PDF: http://www.picaxe.com/docs/picaxe_manual1.pdf
Only thing necessary is to tie the serial in to gnd via 33k, which is pin2 in my schematic.

I'm powering the whole thing with a onespot that reads 9.54V. When plugged into the circuit, all 9v connections show a voltage circulating from 1.22V to 0V and pack again at about 1 second periods. I'm getting about 0.5V out of the 7805's output. The LED's are all dimly flashing with the voltage swings. Any ideas as to what could be happening?

The protection on the 1Spot turns it off for a second or so then tries to restart. My best guess is that you have some kind of miswiring/connection that is taking more than the 1.7A that the 1Spot will provide before protecting, then retrying. I think you're tripping the overcurrent protection.

You are correct! One of the 7805's was funky and causing the 1spot to lash out. Switched the 7805 out and working like a charm, except for no voltage when a button is pushed. I have a start up display that flashes all the LED's, so the PICAXE can send voltage to the transistor and light the LED, meaning that part works, but not triggered by the pushbutton. That's a code problem, so the thread problem is fixed! Thanks guys.