Help Please

[Tos]

Hi Guys and gals

I am a total nuff nuff when it comes to electronics so please be gentle

I want to switch an extra low voltage of around 100 to 150 millivolts at around 200 to 1000 milli amps at around 6khz to 10 khz or higher if posible useing a picaxe, I have several 18X chips so any circuit ideas or descriptions based on this would be very cool

Thankx in advance
Tos

 

[womai]

I guess we'll need a little more details before being able to help:

First. when you say "switch", does that mean you already have a source that provides 200 - 1000mA at a voltage of 100-150mV, and that you want to connect/diconnect? (like a relay or mechanical switch would do, albeit you can't use that here because the required switching frequency is too high). Or does it mean you have something that _needs_ that sort of supply, and you are looking for a circuit that can provide it (and that can be switched on and off at several kHz)?

In any case, 1000mA at 100mV means your source must have much less than 0.1 Ohms of impedance, not an easy thing to achieve if it is supposed to be a constant _voltage_ source (i.e. the voltage is given, and the current has to be provided). Or is it rather that you need a certain _current_, and the voltage has to be regulated, i.e. a constant _current_ source? The solution may be some voltage regulator circuit (like what is used in power supplies to keep the voltage constant), but your particular combination of parameters (very low voltage, relatively high current, and fast switching) could make this challenging.

Telling us a bit about what application this is for - the more details the better - will also keep people from guessing (and missing) wildly

Wolfgang

 

[Tos]

Thankx for you prompt reply Womai I am playing with a solar cell that I have built slightly different from most as I still obtain a power at night. I would not like to say to much at this stage but at midnight I obtain varing power as stated above. I really want to use te picaxe to discharge this voltage through a transformer to raise the voltage to around 4 to 5 volts and I will start the freq at around 50 hz and increase this untill either the transformer or the cell can not keep up.

I hope that this can help you help me

Kindest Regards
Tos

 

[manuka]

a solar cell that I have built slightly different from most as I still obtain a power at night.

?????? Ahem! Tos- there's little THIS new about PV energy, so suggest you explain your setup more fully. Most Forum old hands have had decades of hands on solar experiences, so you can rest easy about spilling the beans to us. Do you just have a bank of (charged) capacitors (or electrochemical storage) for after dark work?

 

[premelec]

Bet he's got it under a street light at night!

 

[premelec]

I tried an edit but it didn't work - take a look at the www.ti.com TPS61200 data sheet - that's an input about as low as you can go without using mechanical contacts... usually we use several cells in series to get high voltages to switch.